Splits and Stolen Bases

Ideas spring from odd places at times, and this particular idea I owe to a rather spirited Millennial with whom I shared an adult beverage in the not so distant past. It just so happens we watched Austin Jackson steal a base and I overheard him mutter something to the effect of “don’t get used to that” — which, considering the sprained ankle Jackson suffered just days after, perhaps Jackson’s spiritual adviser might be interested in a chat. But I digress.

After some discussion, his point was less about Austin Jackson than about stolen bases in general. Stolen bases, he posited, fall off in the second half of the season. I told him I was unaware of such a phenomenon and asked if he had seen research to that end. Indeed, just look at 2014 said my young budding analyst. So I did. If stolen bases were less common in the second half of the season, this could have implications for standard rotisserie league strategy, inasmuch as your approach to your place in the standings.

If you take a peek at 2014 speedsters, it does indeed appear that he is kinda-sorta-maybe on to something. If you look at the actual stolen bases the number is almost always going to be lower, because duh, the second half is shorter (thus not really a half at all. It’s just the second part. Sigh, digression). Therefore, with the statistical wizardry help of one Jeff Zimmerman, below are your 25 stolen base leaders from 2014, sorted by the difference in stolen bases per game in the second half.

name Season Split SB G SB/G Split SB G SB/G total Difference
Jarrod Dyson 2014 1st Half 18 59 0.20 2nd Half 18 48 0.38 36 0.18
Lorenzo Cain 2014 1st Half 12 69 0.13 2nd Half 16 61 0.26 28 0.13
James Jones 2014 1st Half 17 65 0.19 2nd Half 10 33 0.30 27 0.12
Carl Crawford 2014 1st Half 10 46 0.11 2nd Half 13 58 0.22 23 0.11
Ian Desmond 2014 1st Half 10 91 0.11 2nd Half 14 63 0.22 24 0.11
Carlos Gomez 2014 1st Half 17 87 0.19 2nd Half 17 60 0.28 34 0.10
Denard Span 2014 1st Half 15 84 0.16 2nd Half 16 63 0.25 31 0.09
Michael Brantley 2014 1st Half 10 90 0.11 2nd Half 13 66 0.20 23 0.09
Ben Revere 2014 1st Half 26 85 0.29 2nd Half 23 66 0.35 49 0.06
Jose Reyes 2014 1st Half 17 79 0.19 2nd Half 13 64 0.20 30 0.02
Leonys Martin 2014 1st Half 18 90 0.20 2nd Half 13 64 0.20 31 0.01
Jason Kipnis 2014 1st Half 13 68 0.14 2nd Half 9 61 0.15 22 0.00
Jacoby Ellsbury 2014 1st Half 24 90 0.26 2nd Half 15 58 0.26 39 -0.01
Jimmy Rollins 2014 1st Half 19 90 0.21 2nd Half 9 47 0.19 28 -0.02
Charlie Blackmon 2014 1st Half 18 93 0.20 2nd Half 10 60 0.17 28 -0.03
Rajai Davis 2014 1st Half 24 73 0.26 2nd Half 12 56 0.21 36 -0.05
Starling Marte 2014 1st Half 21 82 0.23 2nd Half 9 52 0.17 30 -0.06
Brett Gardner 2014 1st Half 15 88 0.16 2nd Half 6 57 0.11 21 -0.06
Alexei Ramirez 2014 1st Half 15 95 0.16 2nd Half 6 63 0.10 21 -0.07
Dee Gordon 2014 1st Half 43 91 0.47 2nd Half 21 57 0.37 64 -0.10
Elvis Andrus 2014 1st Half 20 94 0.22 2nd Half 7 63 0.11 27 -0.11
Alcides Escobar 2014 1st Half 22 94 0.24 2nd Half 9 68 0.13 31 -0.11
Billy Hamilton 2014 1st Half 38 86 0.42 2nd Half 18 60 0.30 56 -0.12
Eric Young 2014 1st Half 25 62 0.27 2nd Half 5 36 0.14 30 -0.14
Jose Altuve 2014 1st Half 41 93 0.45 2nd Half 15 65 0.23 56 -0.22

So 12 players had higher stolen base rates in the second half and 13 had lower stolen base rates. But what jumps out to me is that four of the top five total base stealers had lower rates in the second half, and considering Hamilton and Altuve, significantly so. This really doesn’t strike me as a huge surprise, considering it’s a long season and maybe there’s some fatigue in them legs. However, no real smoking gun here. But then again, this is just 2014. So I decided to look across a few more seasons, drawing on data back to the year 2006 season, looking at every player to have ever stolen a base in the first half and the second half. And the results were a little unexpected.

Since the 2006 season, there have been 14,829 stolen bases in the first half over 219,456 games played for a ratio of .067 stolen bases per game. In that same time span, there have been 11,549 stolen bases in the 2nd half of the season over 174,168 games played for a ratio of (drum roll) .066 stolen bases per game. Basically, no difference at all. Sorry little buddy, next round is on me.

What does this mean? Probably nothing — but piqued enough is my curiosity that it might deserve a deeper look. Because the grand totals include everyone, pitchers and non-pitchers alike and in that bubbly milieu the real story might just get lost in the noise. If it turns out that burner-types are less likely to keep pace in the second half, then it means stolen bases are coming from new, or different, sources. In the short term if this stability should hold up in 2015, it means you might not be completely safe if you’re killing it in the stolen base category — or alternatively, completely screwed if you’re in the cellar. In part two, I’ll take a look at top base stealers from, say, 2010-2013 to see if it tells a similar story to 2014. Stay tuned.

We hoped you liked reading Splits and Stolen Bases by Michael Barr!

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Michael was born in Massachusetts and grew up in the Seattle area but had nothing to do with the Heathcliff Slocumb trade although Boston fans are welcome to thank him. You can find him on twitter at @michaelcbarr.

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Patrick
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Patrick

Looking at the above data from 2014, it does look like the top steal guys tend decline in the 2nd half.

A couple of interesting area of reseach:
1. Are 2nd half steals buoyed by Sept steals due to call ups?
2. Does 2nd half steals have any correlation to team record? Does a team out of it give up and steal less? Or does a team out of it steal more? Does it depend on the player?