The 2015 Strike Zone, Through July
With strikeout rates soaring and run scoring dipping to generational lows in recent seasons, word came in the offseason that the Competition Committee would be monitoring the expanding strike zone in 2015. Given the scrutiny it is receiving at the league level, I have been tracking the strike zone over the course of the season, with updates at the end of each month. At the following links you can find the updates from the end of April, May and June.
Here are the latest data at the end of July 2015:
| Recent Strike Zone History |
|---|
| Year | Strike Zone Size(sq. in) | Strike Zone Size Below 21”(sq. in) | K% | BB% | R/G |
| 2009 | 435 | 0 | 18.0% | 8.9% | 4.61 |
| 2010 | 436 | 6 | 18.5% | 8.5% | 4.38 |
| 2011 | 448 | 11 | 18.6% | 8.1% | 4.28 |
| 2012 | 456 | 19 | 19.8% | 8.0% | 4.32 |
| 2013 | 459 | 30 | 19.9% | 7.9% | 4.17 |
| 2014 | 475 | 47 | 20.4% | 7.6% | 4.07 |
| 2015* | 477 | 50 | 20.2% | 7.5% | 4.11 |
* Through the end of July.
As I noted last month, the size and shape of the strike zone in 2015 has evolved to very closely match what was called in 2014. This is to be expected, given that umpires are assessed on a nightly basis and there has been no indication from the league that umpires would be directed to call the zone any differently this season than last.
However, walk rates have continued to fall, and strikeout rates and run scoring are trending back ever so slightly in what most would consider a positive direction. An important detail to keep in mind though is how the as-yet-to-be-played, call-up-filled month of September tends to play out in MLB.
| (September – Full Season) Deltas |
|---|
| Year | K% | BB% | R/G |
| 2009 | 0.3% | 0.1% | -0.11 |
| 2010 | 0.8% | 0.0% | -0.17 |
| 2011 | 0.8% | 0.1% | 0.13 |
| 2012 | 0.7% | 0.1% | -0.09 |
| 2013 | 0.8% | 0.1% | -0.12 |
| 2014 | 0.3% | -0.4% | -0.16 |
While walk rates have tended to hold fairly flat in September, strikeout rates have traditionally spiked in the final month of the season. Aside from an anomaly in 2011, run scoring has tended to decrease fairly dramatically too as the regular season winds to a close. Perhaps this phenomenon suggests that September call-up pitchers have been ahead of their called-up batter counterparts. Or perhaps as the season’s games become more meaningful down the stretch, managers have ridden their better arms more heavily to increase the league-wide pitching talent level. Whatever the reason, it is clear that at least in recent history, the month of September has suppressed offense relative to the rest of the season.
As another point of reference, at the end of July last season, the league strikeout rate was 20.3%, the league walk rate was 7.8%, and teams had scored on average 4.11 runs per game. So in reality, for all the talk of the incredible performances of young phenoms entering the league in 2015 and small yet visible improvements in offense, (K-BB%) is higher yet again and runs scored per game are only flat year on year, continuing the trend toward defense that has existed throughout the PITCHf/x era.
Here is a visualization of the strike zones to date in 2015, from the umpire’s perspective:
Another metric that I’ve been tracking is the seemingly widening gap between the size of the strike zone for right-handed hitters and left-handed hitters. Here are the numbers updated thorough the end of July:
| Recent Statistics for (Right-handed Hitters – Left-handed Hitters) |
|---|
| Year | Strike Zone Size (sq. in.) | BB% | K% |
| 2009 | 6 | -1.8% | -0.4% |
| 2010 | 5 | -1.7% | -0.7% |
| 2011 | 5 | -1.0% | 0.0% |
| 2012 | 7 | -1.5% | -0.2% |
| 2013 | 5 | -1.2% | 0.1% |
| 2014 | 17 | -1.4% | 1.4% |
| 2015* | 27 | -1.3% | 1.5% |
* Through the end of July.
The jump in the relative size of the right-handed hitter zone that appeared last season has stayed present and even increased in 2015. It would appear the most significant difference that exists is on the inside edge of the plate for left-handed hitters, which is still called a ball more often than not.
As I mentioned in an earlier update, left-handed hitters have outperformed their right-handed hitting counterparts in both OBP and OPS in each of the seasons in the table. By having the platoon advantage more often and now an even smaller relative strike zone with which to contend, left-handed hitters are enjoying some built-in advantages.
Finally, at times it may be useful to have a formula to describe the strike zone. Of course we know that the zone shifts all the time, due both to expected variables like the height of the batter, but also to unexpected variables like the count and the number of outs. To keep the formula simple, it will ignore all variables other than the horizontal and vertical location of the pitch as it crosses the front of home plate, as well as the handedness of the batter.
A set of elliptical strike zone formulas that have correctly assigned 91.2% of called pitches from 2015 games as balls or strikes are:
RHH: ((px + 0.0208)^2 / 1.0556) + ((pz – 2.4792)^2 / 1.0209) <= 1
LHH: ((px + 0.1042)^2 / 1.0209) + ((pz – 2.4167)^2 / 0.9792) <= 1
In other words, pitches that satisfy that formula are strikes and those that don’t are balls. In the forumula, px is the horizontal location of the pitch and pz is the vertical location of the pitch as it crosses the front of home plate, as provided in PITCHf/x data.
References & Resources:
All statistics adapted from FanGraphs, Baseball Heat Maps PITCHf/x database and Baseball-Reference.
Jon Roegele is a baseball analyst and writer for The Hardball Times. He was nominated for a SABR Analytics Conference Research Award in 2014 and 2015. Follow him on Twitter @MLBPlayerAnalys.
I’ve always heard that the lefty strike zone is bigger, especially on the outer edge…
Outer edge, yes, entire zone, no.
no comment.
I guess I interpret the data here differently especially with regards to the differences between left handed and right handed strike zones. The conclusion that left handed hitters have a built-in advantage because their zone is called smaller is a fallacy. The zone may be called smaller, but it is far more irregular which I think any hitter would tell you is far more harmful than a larger, more standardized zone. The issue is not size, it is consistency. The right handed zone in that graph is nearly a perfect square, with the extreme corners seeing fewer strikes as you’d expect. The left handed zone, while smaller in area, is completely irregular, trending down and away, and leaves far more doubt in a hitters mind what may or may not be called a strike any given day.
The most recent example that got headlines is Bryce Harper on July 31st, the game he was ejected in extra innings for arguing balls and strikes. The strike three called on Harper that final at-bat was 15″ from the center of the plate according to Brooks Baseball, which means it was 6.5″ from the edge of the plate. That pitch was farther outside than the pitch immediately preceding it, 5″ off the plate and just 4″ higher, called a ball.
Even if we are willing to accept that the “recognized” left handed hitter strike zone extends 3″ off the outer edge of the plate, that ball would still be 3.5″ beyond that imaginary line. That’s a distance greater than the diameter of a baseball and nearly to the chalk of the right handed batters box, which had all but been erased by extra innings.
I think any left handed hitter would tell you that they are fine with a “shifted” zone, so long as that zone is called consistently. What you can’t have is umpires taking that extra 3″ and turning it into an extra 6″. There is no rationale for allowing umpires to regularly call strikes on pitches that are half a foot off the outer edge. And I say regularly, because that particular strike that led to Harper’s ejection was not even the most egregious of the day. His first at-bat in that same game saw a Matt Harvey fastball registered at 7″ off the edge of the plate called a strike.
I don’t think hitters from either side would care if the zone was wider in general, so long as it was called consistently and umps stopped giving pitchers those low strikes. It is easy to adjust in-out as long as you have a defined “line in the sand” to base your adjustments on, but having a zone that is expanding down (and in the case of LHH down and away) just isn’t acceptable. Bring on the robots, tell hitters the zone is going to be the plate plus 3″ (baseball width) on each side wide but go back to top of the knees for the low end of the zone.
The data does not address strike variability for LHBs (it could be the case that the zones are more volatile for LHBs, it is just not addressed here) — it does however suggest less called strikes for LHBs. That is definitely an advantage and cannot be construed as otherwise.
Also, this is a fairly ridiculous statement, no?
“I don’t think hitters from either side would care if the zone was wider in general”
Even when called consistently, covering more space is more difficult…
This was true relatively recently. But apparently MLB has trained umpires to eliminate the outside “lefty strike” without correcting the inside “lefty ball”
I am not sure, but I think that the weather is colder in September (relative to the entire season). Could be wrong though. Too lazy to look it up. That would account for lower run scoring.
I think it’s because of the callups, which means more bad batters.
But no bad pitchers? It is easy to test, anyway…
Interesting thought. You’re probably right, although I’m sure April would be a cooler month, and I believe at least this season scoring was relatively higher than months since then. May be a combination of a few factors. I should just test it.
I think it is accepted that despite April being cooler, run scoring is not depressed because “batters are ahead of pitchers in terms of being game ready.”
fantastic visualization! I had also been under the impression that lefty zones were bigger due tot he outside part of the plate, and had not realized the huge benefit they have on the inside.
are these called strikes only?
Why would he be looking at swinging strikes?
I think he was referring to labor strikes.
From watching games with the K zone, it seems that for every strike that is called a ball, there are 8 balls called a strike.
I would like to see the stats for the Joe West crew.Those guys make early dinner reservations.
Let’s get some Robot umps, please. The expanded K zone has really made the game extremely unfair for hitters.
A classic explanation for LHHs’ advantage is that they’re closer to first.
The changing strike zone, together with recognition of framing (which is sort of cheating, actually), do indeed support robotic solution.
Umpiring has improved tremendously with umpires living under the gun, whatever anyone thinks of the strike zone. There are a few stinkers left, but most seem to taking electronic exposure seriously.
The center of the baseball may be nearly an inch and one-half outside the strike zone and still nick the plate. They’re calling it. Low and high seem to be especially annoying to hitters.
It is completely untrue that umpires have become more consistent among each other because they are “evaluated” on a daily basis using pitch F/X. Umpires have their own strike zones, there is wide disparity among umpire zones, and they seem to be completely unresponsive to any evaluation, if there is in fact any.
“they seem to be completely unresponsive to any evaluation, if there is in fact any.”
How would you know this? Can you point me to a study showing that umpires have not been individually changing their zones in recent seasons?
Go on the baseball savant site and look at the individual umpire results from year to year. They show you each umpire’s percentage of balls that were called strikes and strikes that were called balls.
Let’s look at the two umpires with the most extreme zones, Bill Miller (largest zone) and Paul Schreiber (smallest).
Here are their called strikes outside zone percentages from 2012-2015:
Miller
2012: 17.72
2013: 15.92
2014: 17.12
2015: 17.44
Schreiber
2012: 13.20
2013: 12.44
2014: 12.01
2015: 12.24
As you can see, even those these umpires are at the extremes (the average umpire calls around 14-15% strikes outside the zone), there is no attempt whatsoever for them to conform over the years.
It is the same for the other umpires. Extreme umpires remain extreme even though clearly in any kind of “evaluation system” they would be rated as extreme. There appears to be no pressure whatsoever for umpires to conform to any particular standard.
Two other extreme umpires are Eddings (large zone) and Gibson (small). This time we’ll look at yearly strikes that were called balls.
Eddings
2012: 7.00%
2013: 7.21
2014: 6.86
2015: 6.10
Gibson
2012: 11.49%
2013: 10.75
2014: 9.23
2015: 11.35
Again, no attempt to change or conform over the years.
Maybe there are attempts to change but they are unsuccessful. It could be easily tested, either way, if there was performance pay based inversely on the number of incorrectly called pitches.
I’m not buying this. It goes against common sense and those 4 umps stats you posted isn’t a proper sample size. Not to mention all 4 of your umps improved from year 1 to 4. Even without improvement every year they still all improved over the 4 year span.
James Wilson said that they were getting better. Jon Rogele had reported the same thing in July: http://www.hardballtimes.com/the-commissioner-speaks-imagining-a-redefined-strike-zone/
He also reported hat umpires have become more consistent across each other, reproducing the work of Brian Mills
“Where Mills left off, there had been a clear trend toward better overall consistency between umpires across the league that actually extended back to 1999”
Looks like overall they are doing a pretty damn good job. I think it should be repeated in these types of articles that the strike zone that is ‘expanding’, is expanding from what was an inaccurate strike zone that was basically ignoring the rule book. Aside from the LHH bias, this is not bad. I for one would like to see an electronic strike zone, but keep the umpire there for the foul-tips, catcher’s interference, and things of that nature. Oh and please start calling guys out that plant their back foot outside of the back line. I don’t see why they can’t just say you can’t dig out the chalk line with their foot.
“the strike zone that is ‘expanding’, is expanding from what was an inaccurate strike zone that was basically ignoring the rule book.”
I’m glad I’m not the only one recognizing this. Do those complaining about the expanded K zone not remember what it was like over 5 years ago? We’re taught our whole lives the zone is knees to bottom of letters but it was never has been called that low in the MLB. The smaller zone was discussed during games frequently on TV, because it was obvious to everyone. The bottom of the zone begins right below the kneecap according to MLB rules. Hitters like Bonds started juicing, wearing body armor and could take inside strikes for balls and wait for a strike over the plate. Pitchers had to adjust by living in the lower half to avoid HR’s. Umps are getting better at calling the low strike because they see it more often.It’s said that the low strike is the hardest location for umps to judge.
A Strike should be called for any pitch that is over the plate at a hittable height. The new K zone does not do this, and I think this study points to that. Might as well tell these guys to get their 9 irons out the way the zone is being called.
Shave two inches off the bottom and add it onto the top (in other case move the zone up 2 inches)
Isn’t the strike zone three dimensional (at least in practice)? I always see it projected into two dimensions, and I wonder if we are losing any information viewing it this way.
I always thought the plane was at the back of the plate. Like a glass rectangle.
I always thought that the left handed hitting strike zone was larger, especially on the outside part of the plate. Is it really the opposite?
Does anyone have a good guess as to why LHH are getting free balls to the entire inside of the strike zone? I am having a hard time understanding why they are so different. The umpire would setup in his same spot regardless right?
A lot of the issues are related to how the Umpire has to position himself behind the catcher with respect to LHH and RHH.
I think it is less a factor getting free balls and more of a factor of where the bulk of pitches are located to LHH. Pitchers are typically going to attack LHH away so they can’t pull the ball so the zone has shifted away to compensate.
It also seems like LHH tend to set up far closer to the plate than RHH. So many of the best LHH in baseball seem to set up right on the plate with their hands often time drifting out over the plate, Anthony Rizzo being a good example of that. Pitches inside to batters like that just look so much farther in because the batter is so close to the zone.