Why Can't the National League Hit Lefties Anymore?
This site is called the Platoon Advantage and I realized that I have yet to write a post in my tenure here talking about platoons at all. Well friend (unless you are a pie supporter, then you are just a reader, unless you solely support pizza pies, in which case you are definitely a friend, especially if you would like to buy one for me to consume), that is about to change.
I was looking through baseball-reference's league batting splits pages and noticed that the National League OPS versus left-handed pitching is way down this year. Past five years OPS for National League versus RHP and LHP:
| Year | NL OPS VS LHP | NL OPS VS RHP |
| 2008 | 0.752 | 0.741 |
| 2009 | 0.737 | 0.740 |
| 2010 | 0.734 | 0.719 |
| 2011 | 0.711 | 0.710 |
| 2012 | 0.670 | 0.705 |
The American League shows a similar decline with the exception of this year. OPS numbers are still down, but not by the amount that it is in the National League.
OPS has been in decline for a while, but it has taken a huge hit so far this year. A lower number is to be expected, but 41 point difference is much larger than any other year to year total. What is causing this discrepancy? In order to find this, I looked at which teams are performing much worse against lefties than they did last year.
Only four teams have improved on their OPS vs LHP in the NL from 2011 to 2012: The Braves, Cardinals, Dodgers and Brewers. The other 12 teams all have a lower OPS than they did last year. The Reds, Pirates, Giants, Marlins and Padres are the biggest culprits.
What about specific players? Which players performed well against LHP last year and are not this year? The top five qualified players in OPS vs LHP in the NL last year were Matt Kemp, Ryan Braun, Troy Tulowitzki, Giancarlo Stanton and Shane Victorino. This year, Braun is terrible against LHP and Tulowitzki is not quite as good. Both Kemp and Victorino have been better. Stanton has been injured. Albert Pujols also left the league. He had a 0.946 OPS against LHP in 124 PAs.
In 2011, there were 39 qualified players with an OPS against LHP above the league average. 11 of those players have increased their OPS this season, including players like Stanton, Danny Espinosa and Omar Infante who have barely played against any lefties so far. The remaining 28 have decreased their OPS this season, including the injured Michael Morse and the missing Prince Fielder and Jamey Carroll.
We also need to look at players new to the league in 2012. There are 81 batters with more than 10 PAs against LHP this year that were not qualified batters against LHP last season. Of those, 34 are above the 2011 average this year and 47 are below average. It is a possibility that there has been an influx of new or increased responsibility of poor LHP hitters in the NL in 2012.
Has anyone else noticed this or have a reason as to why this could be happening? Let me know your thoughts in the comments section or on twitter @stealofhome.
