AT&T Is the Home-Run Killer of the Millennium
Here’s something that isn’t new to you: It’s difficult to hit a home run in San Francisco. It’s difficult to hit a home run in any ballpark, but, in particular, San Francisco makes it tough. This information is well understood.
So why don’t we freshen things up with a twist? Not only is it hard to hit a homer in AT&T Park — AT&T makes homers more hard than Coors Field makes them easy. That’s clunky, so to put it a different way, AT&T has the most extreme home-run park factor in the league. The most extreme of the pitcher-friendly places, and the most extreme of the hitter-friendly places, just speaking in terms of distance from the average. We all know the ballpark holds most fly balls, but while we were paying only indirect attention, AT&T became the toughest dinger ballpark in 25 years.
This is based on FanGraphs’ own park-factor calculations, and here’s a glimpse of the Giants’ historical year-to-year home park factors. The way these work is that 100 corresponds to the average, and any number under 100 means the park reduces that statistical category. That page shows plenty of different factors, but the one we’re interested in here is, of course, the “HR” column. You can see that homers have been tough in San Francisco ever since they moved into their then-brand-new yard, but that 84 factor has stood up four years in a row. A home-run factor of 84 is a remarkably low home-run factor.
Last year’s highest was 113, a tie between Coors Field and Great American Ball Park. That’s 13 points from the average, while AT&T comes in at 16 points removed. Second-lowest, Marlins Park comes in at 88. It’s not like San Francisco is the only place that makes this tough, but that’s the only park I’m going to put in some context.
We have these numbers on FanGraphs going back to 1974. Since then, the only teams with lower home-stadium homer factors were a bunch of Astros clubs from the 70s and 80s. The Astrodome, in turn, developed a pitcher-friendly reputation. Other than those Astrodome years, which had homer factors ranging between 76 and 83, the lowest home-run factors we have are 84. It’s a tie between present-day AT&T Park and Royals Stadium from the years 1990 – 1991. That’s the most recent comparison. By our own math, AT&T now is the most homer-suppressing park in two and a half decades.
It might seem a little bit strange, at first thought, that AT&T has gotten tougher. The stadium itself hasn’t changed very much. The home-run factor used to bounce around closer to 90. But then, it’s worth remembering that all of this information has to be considered relative to the average, and it’s the average that’s changed. It’s the ballpark context in which AT&T has existed. It’s true that Coors Field made a small tweak to try to cut down on a few dingers, but on the other hand, Citi Field has moved in the fences. Safeco Field has moved in the fences. Marlins Park and Petco Park have moved in the fences. Progressive Field underwent renovations that caused certain balls in the air to take off. One by one, pitcher-friendly environments have adjusted themselves, mostly in the name of fairness. The greater home-run landscape has changed, while San Francisco has stayed where it’s been.
And so we can say this: Over the past four years, there have been 446 home runs hit in Giants home games. That ranks 29th out of 30. At the same time — or, I guess, not exactly at the same time — there have been 650 home runs hit in Giants road games. That ranks 13th out of 30. Just based on these very basic numbers, AT&T has reduced homer output by 31%. Marlins Park is at 26%, with PNC and whatever Oakland is calling it now tied at 20%. This is, yet again, just detail to cement what you already knew, but this is where the home-run spike has gone to die. League-wide, home runs were showing up in modern-day record numbers. Not so for the Giants, not half the time. Overall run-scoring has been much more reasonably reduced, and it’s clear the Giants have been able to survive, but to an increasing extent, Giants home games have featured a different sort of baseball.
Brandon Belt might have my favorite relevant splits. Like many players, Belt has performed better at home, with a career .363 wOBA. In all other ballparks combined, he’s posted a wOBA of .347. However, in San Francisco, Belt has knocked 26 dingers. Elsewhere, he’s knocked 54. He’s had double the rate of homers per fly ball in other environments, and here’s a glimpse of all the batted balls in the air, from Baseball Savant:
Both of those are overlaid onto AT&T, even though, obviously, the road games haven’t taken place there. You can see where Belt’s would-be homers have suffered around Triples Alley, but he’s been productive — more productive! — nevertheless. Psychologically, I’m sure it’s been something to get used to, since hitters want to chance to just go for a jog, but by now I imagine Belt knows he’s hit just fine at home. He’s just had to sprint for it a little more. The Giants probably talk about this a lot.
Home runs are only one part of the action, and as mentioned, AT&T isn’t overall way too extremely pitcher-friendly. It does keep runs down, but no more than Los Angeles, San Diego, or Anaheim. Even the parks that have moved in the fences have, in turn, cost themselves non-homer base hits. Park factors are complicated, and not an easy thing to selectively change. The thing about AT&T is just that we haven’t seen a homer-suppressing park like this in a while. Not by FanGraphs numbers, not relative to the greater league average. It can cause certain Giants hitters to feel underrated, just because the power numbers might not be there. For the most part, they’re there. You just have to think of them right. It’s a slightly different baseball the teams get forced to play.
Jeff made Lookout Landing a thing, but he does not still write there about the Mariners. He does write here, sometimes about the Mariners, but usually not.
Just once, I’d love to see a new stadium built which has Forbes-esque type dimensions, without the management going apey in a couple of years about all the lost home runs and then yanking in the fences. Then try to tailor the club to the wide open spaces.
I’ve thought this exact same thing many times. Build an enormous stadium and go get bunch of speedy OF to chase down all the now-warning track fly balls from other teams’ one-dimensional sluggardly sluggers. Meanwhile, play small ball on offense. The huge park would have a huge positive effect on your pitchers – fewer HR, fewer runs, fewer high-stress innings leading to fewer pitches, all leading to more innings from starters.
However, the trend has been to go away from one-dimensional bat-first sluggers and this off-season is just another example of that. so I’m not sure it would play as well now as it did 10 years ago. You also have to wonder how it would play to fans. Yes, they would come out for a winning team no question, but how is it going to impact the fan base when you have an 80 win team with the best offensive player going .280/20/85?
Sounds a lot like the Royals the last few years…
I would agree with all of this except the high-stress innings part. There would be more baserunners because there’s more room for the outfielders to cover and fewer homers to clear the bases. The Giants have been about as stressful a team as can be imagined, to judge for example by the average leverage index of their relief staff.
Mays great catch at the Polo Grounds in 1954 was made a 420 feet. AT&T demands defense. That RF is among the toughest in baseball. BTW, the Park Factor for triples is a skosh over 1.3.
Barry Bonds had no trouble hitting homers there..
And lefties have a MUCH more extreme HR factor (81 vs 86) than righties. Just incredible what Bonds + steroids was capable of.
And the record for most HR in a WS was set in 2002, when the Giants played the Angels, and the Giants set a WS record for team HR. Though to be fair, only 6/21 HR were hit in Pac Bell, as it was known then.
Samardzija is always a home run risk. Wouldn’t you think the Giants would do their best to schedule him at home as much as possible? He had more IP away this year (not sure about starts, though).
They didn’t change their order at all over the course of the season. Also, Bumgarner’s HR/9 was basically the same as Samardzija’s last year.
As Jeff notes, this isn’t news to FanGraphs readers but the overlays show pretty clearly, it’s not the park itself — Belt’s had what, 3, maybe 4 away HRs that wouldn’t have left AT&T? — it’s the setting. SF residents know how heavy the air is at night and wind is another obvious factor. I’d love to see two follow-ups:
1) Day/night HR-factor splits at AT&T over the last 4 84-factor seasons.
2) A little sports science using the Statcast data. How much more velocity/launch angle is needed in AT&T vs. other parks to achieve HRs? (Or some video ABs of say Belt, having an AB on the road and at home with the same exit velocity/launch angle and see the difference in outcome.)
I don’t think of SF as having “heavy air”, water vapor makes the air less dense. The cold temps during the season could really be a factor, though.
Low temperatures (mid-50’s even in the summer) and being at sea level is the entire thing. The water vapor or “heavy air” actually helps balls fly farther, as you said.
Yep. No matter how many times you tell people this, they will never believe it. Unless there is actual precipitation in the air (fog, mist, rain), humidity actually makes the ball go ever so slightly farther. In practice, it has such a negligible impact that it doesn’t really affect things at all but what impact it has is slightly positive, not negative.
However, as you point out, temperature has an impact and SF can be cold during the summer without a doubt.
Yeah, having played in the Southwest, I’m one of those no matter what’s. Las Vegas is 2000 elevation, granted, but Phoenix is only 1000. 5% humidity is not slowing down any balls.
That includes fall ball, winter ball, and night ball.
“humidity actually makes the ball go ever so slightly farther.”
Wrong. http://www.baseballprospectus.com/article.php?articleid=13057
Humidity makes the ball heavier and “squishier”, which makes it travel less far.
Given the same initial velocity vector, a ball will travel (slightly) farther in humid air than in dry air (of the same temperature and pressure). However, as you say, it’s more difficult to impart that initial velocity when the collision between ball and bat is less elastic because the leather in the ball (and to a lesser extent, the wood in the bat) has softened due to ambient humidity.
Which, of course, is why they keep the balls in a humidor at Coors, rather than trying to make the air in the stadium more humid.
For a while after the “HR surge” started in late 2015, I was wondering if MLB had quietly started ensuring that games balls in every ballpark were being kept at a standardized humidity, and that humidity was lower than ambient for most parks in the summer. But that’s not the kind of thing they could do for very long before everybody knew about it.
Are you familiar with the marine layer?
http://m.mlb.com/news/article/33487892//
I’m somewhat curious about how we use park adjustments for hitters vs pitchers. In my experience, people tend to lean toward offense when talking about park factors. It is generally accepted around here that wRC+ is the tell-all offensive stat, but we don’t treat any park-adjusted pitching stats the same way. I think that may be because we understand offense better and aren’t sure how to completely separate defense and pitching, but I still think FIP- is more telling than FIP when discussing true talent, even though FIP is used much more often.
Just as a quick illustration: Bumgarner had a 2.63 FIP at home last year, but a 3.91 FIP on the road. His FIP- was actually higher than both Jon Gray and Tyler Anderson. He’s obviously one of the best pitchers in the game, but we need to put his numbers in context the same way we do with Rockies hitters. (even if not quite to the same extent)
Just an observation. Curious what people think.
For sure Bumgarner has benefited from the park. But it’s also true that his Hard% was a good deal higher on the road last year (33.6% vs. 29.6%), so the difference wasn’t entirely the park.
Oh yes, absolutely. You also have to factor in things like standard home-field advantage, among others. There are plenty of caveats when discussing individual players, whether it’s for the Giants, Rockies, or anyone else.
What I was really driving at is the tendency to leave out park factors when talking about pitchers. I was shocked when I saw that Bumgarner was outperformed by 2 Rockies last year because I’m always looking at the unadjusted stats.
I freely admit that standard stats overrate all giants’ pitchers, but they also underrate all giants’ hitters.
I think the point is that even though standard stats underrate Giants’ hitters, we use adjusted stats for offense more freely so this is less of a concern.
wRC+ shows up right away on Posey’s player page, but you see FIP instead of FIP- on Bumgarner’s.
All the comments thus far have been excellent–except this one.
As we are constantly being told that chicks dig the long ball and fans NEED higher scoring, it’s unsurprising that this park’s extreme lack of dingers means the terminally unpopular Giants play in front of basically empty crowds.
Clearly they should follow the lead of other pitcher friendly parks and move the fences in to try and match the unshakable popularity hitter friendly parks like Cincinnati, Milwaukee and Guaranteed Rate Field have led to.
That’s right – Home Runs sell tickets and nothing else. The Giants are terminally unpopular because they don’t hit home runs. Winning 3 titles in 5 years has no effect on popularity.
Winning helps, but the Giants essentially sold out every home game even before they started winning World Series there.
Fair. They are also in a large market, and they are the only professional sports team actually in San Francisco (since the 49ers moved to Levi’s Stadium). Lots of factors in the Giants favor. The bottom line (as you point out) is that dropping wangers isn’t the only factor in selling tickets.
It’s an incredible ballpark experience for kids and adults. Gorgeous field and views.
I like the park as it is, except maybe the fence could be a little lower in places. For me, singles with runners in scoring position are more exciting than homers.
In before Barry Bonds
(nope)
” Even the parks that have moved in the fences have, in turn, cost themselves non-homer base hits.”
You mean, the non-homers turned into homers. It’s very strange to think of a homer as “costing a double”.
I believe he meant that by moving in the fences, some singles get turned into outs because the outfielders have less ground to cover.
“AT&T makes homers more hard than Coors Field makes them easy.”
Remember this 20 years from now when all the HoF voters who just kept Larry Walker out (again) trip over themselves in their rush to anoint MadBum.
Of course, Walker played primarily in the pre-humidor days. So regardless of how absurd it is that Walker isn’t in, that quote doesn’t quite apply…
Larry Walker was helped as a hitter by Coors an order of magnitude more than MadBum has been helped as a pitcher by ATT.
Bumgarner’s career splits
.225 / .279 / .340 in ATT
.238 / .283 / .381 in other parks
Walker’s career splits
.380 / .461 / .709 in Colorado
.282 / .372 / .500 in other parks
This would be a good point but for the existence of the “inverse Coors effect.” The problems Rockies hitters have adjusting when they hit on the road, and the causes for those problems, have been thoroughly discussed and debated elsewhere, but IMHO it’s a huge and oft-overlooked issue. So far as I know, there is no “inverse AT&T effect”–though admittedly I don’t have the data in front of me, I can’t think of a reason why MadBum’s pitches would move substantially differently at Dodger Stadium or Petco (or really any park besides Coors) than they do at AT&T.
I’m sure Coors helped Walker more than AT&T helps MadBum, mostly due to the fact that Walker played pre-humidor as Toddfather points out, but “an order of magnitude” more? I’m skeptical.
Completely agree with this. Coors is still the most extreme park, but with the humidor and the inverse Coors effect, it’s at least in the same discussion as AT&T and not an absurd outlier.
Last data I saw looked the boost it gives to opponent’s offense and suggests the park factor should be closer to 1.1 than 1.2. Pulling home vs road slash lines doesn’t really tell us much at this point.
Although it’s probably impossible to prove, i do have the feeling that there is a kind on inverse at&t effect in the sense that some giants’ pitchers who might otherwise try to modify their general approach to pitching (giving up a lot of fly balls) may not do this because in any case they won’t give up many homers at at&t, and this bites them when they’re on the road and they can’t get away with it. I would put bumgarner and cain in this category. I think it may also be affected by bochy’s decisions when to pull bumgerner–like pitchers in general, bumgarner gives up more hard-hit balls when he gets tired, but bochy tends to leave him in anyway. He’s encouraged to do this because at home even if the ball is hard hit it probably won’t go out, which adds to the general impression that bumgarner doesn’t get tired like normal pitchers, but bochy also leaves him in on the road where it’s harder to get away with.
“…whatever Oakland is calling it now…”
Oakland calls it the “Coliseum.” Don’t know what you guys in the press call it.
🙂
But what about the overall runs scored vs other parks, is it lower than all of them? You would think it would be, though of course you can’t put that all down to the park with Bum and Cueto pitching there.
Also don’t understand how Belt has been more productive at home, that overlay image is tough to decipher.
The way we calculate Park Factors controls for the players on the teams. The Park Factor for AT&T is the same, regardless of who pitchers for the Giants. http://www.fangraphs.com/library/principles/park-factors/
The complete list of Park Factors is here: http://www.fangraphs.com/library/principles/park-factors/
You can sort by “HR” to see the PF of 84 that Jeff cites here. If you sort by “Basic” you see that AT&T is still the most extreme pitchers park, but it is much close to average. It gets a pulled up from being triple-friendly.
Intuitively it isn’t surprising to me that belt has overall better stats ar home. He’s an extreme line-drive hitter, he doesn’t hit the ball deep so often. There’s just more open terrtory for him to hit line drives into at home