The Absurdities of Batter/Pitcher Match-Up Numbers

With all due respect to the Dillon Gee–John Gast match-up in St. Louis tonight, there’s one marquee pitching match-up on the schedule for tonight’s games: Felix Hernandez vs CC Sabathia in New York. Neither pitcher throws as hard as they used to, but they’ve both managed to adapt to life without their fastest fastball, and both remain among the best starting pitchers on earth.

Sabathia, in particular, is lethal against left-handed hitters. Witness his strikeout rate by batter handedness, in graph form.

Not only is Sabathia showing no signs of decline against LHBs, he’s actually getting better against them, as he’s learned to just destroy them with dominant sliders. While he’s allowed LHBs to post a .281 wOBA against him for his career, it’s just .261 since the start of the 2011 season, as the reduction in velocity hasn’t done anything to make his slider against LHBs any less lethal.

Right-handers have always done a little better against him, since he swaps out half of his sliders for the less effective change-up, and the sliders he does throw dive in towards opposite handed hitters. He’s still been plenty good against RHBs, just not quite as good, and in a very small sample of 2013 data, his performance against RHBs has gone the wrong the way, posting a 4.34 FIP and 4.18 xFIP, both of which would be the highest season marks he’s posted since 2003. He’s almost certainly better against RHBs than those numbers show because of the sample size, but it’s not hard to believe that the reduction in velocity hurts him more against RHBs than LHBs.

So, if you’re matching up with CC Sabathia in 2013, it probably makes sense to stack right-handed bats against him, or at least defer to right-handed hitters over left-handed hitters when there’s not a big gap in talent between the options.

Tonight, the Mariners are using Raul Ibanez as their designated hitter against CC Sabathia. Raul Ibanez is left-handed. The Mariners are doing this because Raul Ibanez has okay career numbers against Sabathia. The Mariners are starting a left-handed hitting DH who can’t hit lefties against a lefty killing LHP because of batter/pitcher match-up data. And it is perhaps the perfect example of how not to use numbers.

Ibanez has faced Sabathia 52 times in his career, hitting .250/.308/.458 in those 52 plate appearances. That’s not great or anything, but it’s not totally embarrassing, the way you might expect Sabathia/Ibanez match-up numbers to be based on their own individual platoon splits. But, it’s helpful to put those numbers in context. Specifically, to note when those plate appearances happened. Here’s the breakdown by year:

Year	PA	H	2B	3B	HR	BB	SO	BA	OBP	SLG	OPS
2002	9	3	1	1	0	0	2	0.333	0.333	0.667	1.000
2003	9	4	0	0	1	0	2	0.500	0.556	0.875	1.431
2004	11	1	0	0	1	1	3	0.100	0.182	0.400	0.582
2005	6	1	0	0	0	1	2	0.200	0.333	0.200	0.533
2006	4	1	0	0	0	0	1	0.250	0.250	0.250	0.500
2009	4	1	1	0	0	0	0	0.250	0.250	0.500	0.750
2010	3	1	0	0	0	1	0	0.500	0.667	0.500	1.167

In 2002, when Ibanez went 3 for 9 with a double and a triple against Sabathia, Ibanez was a 30-year-old who posted a .374 wOBA, the best mark of his career. Sabathia, on the other hand, was a 21-year-old in his second big league season who hadn’t yet figured out how to strike out left-handed hitters. In fact, back then, Sabathia had a higher strikeout rate against right-handed hitters (17.7%) than left-handed hitters (13.7%), as he threw a slower curve instead of his power slider, and the curve didn’t work very well against LHBs.

For the first three years of his career, Sabathia just wasn’t that great against LHBs, posting a combined strikeout rate of just 15.1%. He really took off in 2005 — when he junked the curve and adopted the slider — as his K% against LHBs jumped to 27.4%, and it hasn’t been below that mark since. Learning how to blow lefties away was the first step towards him becoming a dominant starting pitcher, something he was not in his first few years in the big leagues.

So, just for fun, let’s redo Ibanez’s career numbers against Sabathia, broken into the two parts of Sabathia’s career by dominance against lefties: 2002-2004, and then 2005-present. First, Sabathia the contact pitcher versus lefties.

Year	PA	H	2B	3B	HR	BB	SO	BA	OBP	SLG	OPS
2002	9	3	1	1	0	0	2	0.333	0.333	0.667	1.000
2003	9	4	0	0	1	0	2	0.500	0.556	0.875	1.431
2004	11	1	0	0	1	1	3	0.100	0.182	0.400	0.582
Total	29	8	1	1	2	1	7	0.286	0.345	0.630	0.975

And now, Sabathia the strikeout pitcher against lefties.

Year	PA	H	2B	3B	HR	BB	SO	BA	OBP	SLG	OPS
2005	6	1	0	0	0	1	2	0.200	0.333	0.200	0.533
2006	4	1	0	0	0	0	1	0.250	0.250	0.250	0.500
2009	10	1	1	0	0	0	4	0.100	0.100	0.222	0.322
2010	3	1	0	0	0	1	0	0.500	0.667	0.500	1.167
Total	23	4	1	0	0	2	7	0.190	0.261	0.257	0.518

Back when Ibanez was at his peak in his Kansas City years and Sabathia didn’t yet know how to strike out left-handed hitters, Ibanez posted a .975 OPS against him. In their match-ups since then, Sabathia has shut him down the way you’d expect a dominant lefty starter to shut down a left-handed hitter with problems against LHPs.

In other words, the entirety of Ibanez’s historical success against Sabathia dates back to a decade ago, when Ibanez was in his prime and Sabathia was an entirely different pitcher. Ibanez is now 40-years-old, and Sabathia is going to attack him with an out-pitch he simply didn’t have 10 years ago. 10 year old data is suspect for many reasons, but to use match-up data from 10 years ago when one player is is eight years older is hilarious. And yet, this is the kind of data that some Major League managers still use to fill out the line-up card.

There probably are some hitters who just hit better against certain pitchers than their traditional splits would suggest, but you cannot identify those match-ups using historical match-up data. In The Book, the issue of batter/pitcher match-up data was studied extensively, and you can read most of that chapter for free via Amazon. The summary is reproduced below:

You see, we’re not saying that it doesn’t matter which pitcher is facing which batter. Every person is different, and there’s no reason to think that two overall equally talented pitchers, but talented for different reasons, will necessarily have the same success level against the same hitter. However, you can’t tell by looking at the numbers from 25 or 60 PA. There is simply too much noise masking the truth under those numbers. You can’t say Edgar owns La Familia Cormier, or that Mussina owns Varitek, because, well, look at the numbers. The numbers don’t support your statement, because of the small sample sizes. For you to say that a certain hitter owns a certain pitcher, you have to go beyond the numbers. You have to look at the specific traits of these players…

The book then goes on to identify some traits that make certain batter/pitcher match-ups more favorable than others, with handedness being the primary one. But none of that even factors in here. Raul Ibanez does not have the platoon advantage against Sabathia. Sabathia is not the type of lefty who lives off his change-up and thus demonstrates some reverse platoon splits; in fact, he’s the type of lefty who absolutely destroys left-handed hitters.

But, here we are in 2013, and Raul Ibanez is starting at DH against CC Sabathia. This is an example of where some data is far worse than no data, because without access to Ibanez’s career numbers against Sabathia, no one would ever think that starting him tonight was a good idea. Batter/pitcher match-up data is worse than nothing, because it not only doesn’t inform a manager of anything useful, it will trick him into doing things that just don’t make logical sense.

At the end of the day, this instance of bad data driving decision making isn’t going to have a huge result, because the 2013 Mariners season doesn’t hinge on this game, and it’s not like Justin Smoak or Jesus Montero are world beaters either. The Mariners are choosing Ibanez over two right-handed hitters, but they aren’t good right-handed hitters, and with Felix Hernandez pitching, they stand a decent chance of winning no matter what their DH does tonight.

But, this is the kind of move that shows how far major league managers are removed from the advances that front offices have made. MLB teams have gotten a lot smarter, but even with a flood of smart people working for big league clubs, stuff like this still happens. In 5, 10, 20 years, whenever it is that MLB starts hiring managers who understand a junk stat when they see one, we’ll look back at some of these decisions and wonder what took so long. For now, we can wonder how long it will take before a billion dollar industry stops letting people make obviously nonsensical decisions.