How Unlikely Is Daniel Murphy’s Streak?
Daniel Murphy chose a really good time to play some really good baseball. He’s hit home runs in six straight games, with a chance to extend that streak once the World Series commences on Tuesday. This is a record for postseason play, as you may have learned if you’ve paid any attention to baseball reporting in the last three days.
However, it’s certainly not unheard of. Since 1914, as far back as Baseball-Reference’s game-by-game records go, 28 players have managed a regular-season home run streak of six or more games*. I will not overload you with the full list, but it includes names both very familiar (Gehrig, Mays, Griffey, Bonds) and obscure, folks you’d fully expect on the list and others who would make you scratch your head.
* The standard I used allows a streak to remain intact if a player had no plate appearances in a game, similar though not identical to the official rules governing hitting streaks. This actually arose among the 28, notably with Graig Nettles. In 1984, Nettles hit homers in two straight games, got two games off, homered in his next two, took two more off, and homered in the following two. I also permit a streak to carry over between seasons, which put 1997-98 Mark McGwire on the list.
Going into October, Murphy would have been one of the head-scratchers. In his seven seasons, his highest home-run total is 14, produced this season. He simply lacked the power to be a reasonable candidate for such a feat — until he flipped the switch and lit up the Dodgers and Cubs.
Is Murphy the unlikeliest of the players who have put together a homer streak of six games or more?
To produce an answer, I looked at the seasons in which those on the list did the deed, and took their rates of home runs per plate appearance (HR/PA). I went by season rather than career because such a streak is an event likeliest at a player’s peak, and the chances go up much more than linearly with rising rates. The HR/PA stat seemed better than raw homer totals because probability per time up is more germane to the nature of a streak than mere accumulation.
As I’ve noted, homer streaks are no shock with some players. In 2001, Barry Bonds homered in 10.99% of his plate appearances. He had two separate six-game homer streaks, one in April and one in May. This inaugurated the golden age of home run streaks. Ten of the 28 streaks occurred in just six years, from 2001 to 2006. (As for why they happened in that span, discuss among yourselves.)
Bonds’ 2001 is the top HR/PA rate on the list. The lowest would belong to… Daniel Murphy, with 14 homers in 538 PA for a 2.60% rate. The hitch is that he’s made his streak in the postseason, so regular season numbers are, if not irrelevant, at least incomplete. Adding his postseason numbers to the regular season gives him 21 for 577, coming out to a 3.64% rate.
That’s a very low rate for a homer streaker, but two other players beat him out. Second lowest on the list is George “Highpockets” Kelly. He made his streak for the New York Giants in July 1924, in a year when he hit 21 round-trippers in 627 appearances for a rate of 3.35%. (Interestingly, despite the Polo Grounds being a great place for dead-pull power, Kelly’s whole streak was on the road, mainly at Wrigley Field.)
For the lowest rate on the list, we go to someone who actually beat the streak criterion. Out of the first 28 players with homer streaks at least six games long, six have gone longer. Tied for the record at eight are Dale Long (1956), Don Mattingly (1987), and Ken Griffey Jr. (1993). Behind them, at seven games, are Jim Thome (2002), Barry Bonds (2004), and the 2006 season of our homer-rate anchorman… Kevin Mench.
Mench, who honest to goodness I did not remember had played baseball until he popped up on this list, did not string together his streak in his best power season, or second-best, or third-best. He did it with a mere 13 home runs in 482 PA, a rate of 2.70%. He hit more than half of his season’s homers in an eight-day, seven-game stretch in late April, against the Devil Rays, A’s, and Indians. Six of the games were at home in Arlington, Texas.
That combination of obscurity, low power, and pushing his streak to a seventh game makes Mench’s run easily the most improbable of the 28 who did it in the regular season. As for being more unlikely than Murphy’s, so far it is, with two caveats.
First is degree of difficulty. Murphy’s done his streaking against, not just playoff teams, but super pitchers. His streak includes dingers off Clayton Kershaw, Zack Greinke, and Jake Arrieta, who will be gold, silver, and bronze in some order in the NL Cy Young race. Jon Lester’s no slouch either. Mench’s streak included three games against the Devil Rays, who were still in the laughingstock phase of their existence.
The second caveat is that Murphy’s streak is not over yet. It may fade out in the long wait for Game One, but it’s a bold prognosticator who would take that as a given. If he can stretch it for one more game, the title may be his. If he manages two, it’s definitely his.
That just one more reason to look forward to Tuesday. And maybe Wednesday.
A writer for The Hardball Times, Shane has been writing about baseball and science fiction since 1997. His stories have been translated into French, Russian and Japanese, and he was nominated for the 2002 Hugo Award.
My very rough estimate on Murphy’s six-game HR streak:
He averaged just short of one homer every 10 games, so if the probabilities are independent it would be a (1/10)^6 or a 1 in a million probability. If you want to allow for him being on a “hot streak”, and double his chances of hitting a homer in each game, the odds of the six-game streak are still about 16,000 to 1.
To be fair, you can’t really count the first one. Murphy is going to hit a home run at some point. So the real question is hitting one in the game specifically after that (and after that, etc.). So using your math that would be either 1 in 100,000 or 1 in 3,200.
Good point, you’re definitely right about that.
I don’t really believe in hot streaks, but I do believe players are capable of adjustments (mechanical tweaks, age, health swings, etc.) that shift their true talent level for hitting home runs over time. Like supposedly Murphy has rejiggered the timing of his plant foot, which has allowed him to drive the ball better. Of course this could all be ex post facto reasoning for his streak, but again, I think it’s certainly possible that his “true” power rate at this moment is better than his career rate. Having said all that, I think your one in a million odds are closer to Murphy’s actual chance of pulling off homers in 6 straight.
I don’t understand how one can “not believe in hot streaks.”
If you’ve ever played any sport in your life you would know there are cycles when you are just locked in, and cycles were you can’t get out of your own way. If there was no such thing as a hot/cold streak we could simply take a couple games of data and know how a player would perform for their entire career.
I don’t really believe in “streaks” either, with Brian’s caveats. In the first place, whether you believe in streaks or not, “a couple of games” is a couple of orders of magnitude too small of a sample size. But I’m sure you didn’t mean that literally. Brian is not saying that players’true abilities don’t change from year to year; he is saying that they do. Technical or strategic adjustments can dramatically change your effectiveness (see Collin McHugh for one recent example). Similarly, injuries that are moderate enough to “play through” but severe enough to impact performance are common, too. Those kinds of things don’t just happen year to year, but month to month or even game to game. So there will never be a way to project an entire career from a small sample size. But if you make the sample size small enough, you can create the illusion of a hot or cold streak. If a hitter is 100 points below his batting average over a 6-game period, we say he’s on a cold streak. If he is 100 points over his average, we say he’s on a hot streak. But both sequences happen randomly all the time, in reality.
Yes, everyone knows that clustering exists. That’s not what they’re disputing.
It’s not really a question of “believing in hot streaks”. Events cluster, and over any series of trials you’ll see plenty of 9-for-20’s, and 0-for-23’s, etc.
It’s more a question of “do you believe that this streak has predictive value”, i.e., does that 9-for-20 streak (or 17-for-43 or 6-game HR streak or whatever) generally portend continued success/more hits in the next game(s), or does the player tend to drop back in line with “true talent” or career averages? The lion’s share of evidence shows that streaks have little predictive value, we just do a really good job of identifying them after the fact. (See also the teams that have swept their LCS series and their lack of success in the World Series)
I guess the Cubs fans now know what the Pirates and Cardinals felt like facing Jake Arrieta during his unsustainable and unlikely streak.
Karma (aka Lady Luck) always has a way of coming back around to get ya….
Jake Arrieta 2014-2015: 12.3 WAR
Daniel Murphy 2008-2015: 13.8 WAR
They are not equivalent talents.
Well obviously. I think he’s commenting on how Murphy’s otherworldly streak is similar to Arrieta’s otherworldly second half.
Murphy is a 40 grade power hitter who hit 7 home runs in 9 playoff games. That is why it is more unlikely. If Murphy had a streak where he struck out 5 times in 3 months, that would be similar to Arrieta’s streak, as Murphy is a plus plus contact hitter.
There is no statistical predictor for Murphy’s dominant power hitting. He had never hit 5 home runs in a month prior and only once had consecutive games with home runs across his career prior to this October. Arrieta’s 2014 FIP was a close predictor of his 2015 ERA. Nothing in Murphy’s profile suggested the best power hitting run in postseason history.
Actually, no, Arrieta’s 2014 FIP (2.26) was *not* a “close predictor” of his 2015 ERA (1.77). While it indicated that Arrieta could have a very good season, he surpassed the FIP indicator by nearly a half-run. That is a substantial difference.
Of course, if any credible preseason sources projected that Arrieta’s 2015 ERA would be below 2.00, or that any specific SP would have an 88.1 IP pace of 0.41 ERA and 0.623 WHIP (Arrieta’s final 12 starts), please cite or link them.
Jake Arrieta 2011-2014: 5.5 WAR
Daniel Murphy 2011-2014: 8.2 WAR
Arbitrary endpoints are fun.
where and how do you get 5.5 war for arrieta…
Jake Arrieta 2011-2014: 14.2(bwar) 14(fwar)
simple math is fun…
… except when you can’t read:
Arrieta from 2011 through 2014 has 6.7 fWAR. Murphy over the same time period accumulated a 9.7 fWAR.
Baseball-Reference (“bwar”) for Arrieta (pitching) during each of the years referenced, 2011-2014:
Year 2011: 0.7
Year 2012: -0.8 (“negative 0.8”)
Year 2013: 0.3
Year 2014: 5.3
The fun simple math still produces a 5.5 WAR for Arrieta 2011-2014. It appears that “state the obvious” tried to shoehorn Arrieta’s 2015 WAR (8.7) into the defined 2011-2014 time frame, which, at a minimum, was incorrect.
Highpockets Kelly, another of the many Hall of Famers on those early ’20s Giants. Doesn’t look like he deserves to be there, but a pretty good player.
Frankie Frisch and Bill Terry are buying the next round for you and High Pockets.
Presenting this as more of a fun fact than a “stat” but…
in 2015, Jake Arrieta surrendered 10 home runs on 3,438 pitches
in 2015, Clayton Kershaw surrendered 15 home runs on 3,392 pitches
in 2015, Zack Grienke surrendered 14 home runs on 3,239 pitches
in 2015, Jon Lester surrendered 16 home runs on 3,185 pitches
Obviously one does not have the means to do something similar for the rest of the streaks. But the odds of these particular pitchers giving up a string of home runs seem very, very low.
That would be like, if Ben Revere hit 6 in a row.
I’m glad this article was written (sort of), because I was thinking this may not be the most home runs in a post season yet, but based on 5 of these HR being off of the 4 pitchers that you mentioned is absolutely insane. I don’t think I’ve ever seen anything like this in my lifetime when the opposing pitchers have been Cy Young quality pitchers for the most part.
It’s ludicrous odds. Murphy has gone to plaid.
I think Nettles had the most unlikely home run streak. He was known for his power, but he turned 40 during his streak and was hitting only .212/.313/.356 in mid-August before the streak began. Nettles also recorded only 18 at bats in the six games, hitting 7 home runs. Mench hit 7 home runs in 29 at bats in his streak while Murphy has 6 home runs in 25 at bats.
Did Nettles hit them against Kershaw, Greinke and Arrieta?
Yes he did but to be fair, they were much more susceptible to the long ball prior to being born.
He hit them off some pretty good pitchers including Doc Gooden, who finished #2 in Cy Young voting, and John Denny, the defending Cy Young winner who had a 1.45 ERA at the time.
SABR research has always treated each at-bat as an isolated match-up between the pitcher’s true talent versus the hitter’s true talent. It’s very likely that each component fundamentally varies over some fixed range and that each at-bat is not an independent event like a true coin flip.
If we’re going use the “degree of difficulty” approach, then we should also acknowledge that, without Kyle Hendricks and the 2015 version of Fernando Rodney, Murphy’s six-game HR streak would not exist.
As impressive and unlikely as Murphy’s recent run has been, elevating him over other streaks by emphasizing that he HR’d off of Kershaw/Greinke/Arrieta seems a little like cherry-picking data to support the conclusion.
This is a pretty foolish post, John G. Just because he went deep against two mediocre pitchers, that doesn’t mean it’s not impressive that 5 of his 7 HR were against high-end pitchers. His degree of difficulty, overall, was off the charts with these pitchers, and it *should* be elevated over the other streaks. Nobody has put together a streak like this against nothing but aces.
I not only remember that Kevin Mench played baseball, I remember that streak. His explanation was that he’d been wearing the wrong size shoes his whole life, and finally figured it out. When he went up a size, he felt liberated or something, and suddenly he couldn’t stop hitting home runs.