As we all know, Addison Russell is an exciting young shortstop for the Chicago Cubs. At only 22 years of age, he is already a key component to the best team in baseball. Dating back to his days as a prospect, he has often been compared to Barry Larkin.
So why does he suck against left handed pitching? As evidence look at this chart from 2016:images/articles/2016-06-30/2016-06-30-2016-performance-splits.png
Against same handed (vs R) pitching Addison has put up a .780 OPS that would rank 12th in baseball for 2016. But when facing lefties, he puts up a .560 OPS that would even cause Jose Macias some shame. And this is despite what should be a platoon advantage. In 2016, MLB right handed hitters have a .730 OPS vs lefties and a .724 OPS vs right handed pitching.
It was the same trend last year, as well. If we look at Addison's career splits, they look like this:images/articles/2016-06-30/2016-06-30-career--performance-splits.png
So what gives?
The key takeaway from these tables is that the very biggest part of the differential in OPS comes from the batting average. His walk rate is a bit better against lefties and his power is a bit better against right handers. But there is a huge difference on his batting average on balls in play, which causes his batting average against lefties to be almost half what it is against righties.
Well, that gives the proximate cause for the performance difference! But why is there such a staggering difference on his BABIP against lefties and righties?
Let's take a look at his splits on batted ball data. We'll look at the career numbers again.images/articles/2016-06-30/2016-06-30-career-batted-ball-splits.png
There is a remarkable similarity in those lines with one very notable exception. The Pull vs Center vs Opposite field numbers are almost exactly the same. The LD/GB/FB numbers are almost exactly the same. The Soft/Medium/Hard splits are similar, with some of the hard hit balls shifting to soft hit. That would help explain the difference a little bit.
The big difference there, though, is the enormous difference in the number of popups, or IFFB%. At the major league level, a popup is just as sure of an out (or an error scored as an out for the hitter, anyway) as a strikeout. Those 10-11 popups alone account for a significant percentage of the difference in his BABIP.
So, then, why does he hit such a high percentage of popups against lefties?
For that answer, I went to the statcast data. After a couple hours of searching, I have not found any compelling answers. There is this difference in the way that lefties and righties are locating the ball:
(lefties are on the left, of course!)
The biggest difference there is that he's being pitched down and in a lot more by left handers. But also look at the ratio of the pitches away and outside of the zone. Right handers work him down and out of the zone by nearly a 4-1 ratio (241 / 67). For lefties, that same ratio is almost exactly 2-1 (67 / 33).
In the end, it is hard to tell the true root cause for why Addison is hitting so many popups against lefties. But those popups alone go a long way to explaining the difference in his performance against southpaws. The remainder is likely just small sample size bad luck.