Lefties have a huge advantage on the mound. Consider that about 10 percent of the public are lefties but this year 27 percent of the pitchers who qualify for the ERA title are lefties. So that means they are about 2.7 times better simply due to being left-handed.
Here's an interesting interview with an aerospace engineer who studied the benefits of being left-handed in baseball, generally.
Of course, we focus just on the hurlers in Pitching by the Numbers, this week with two charts. The first is the best lefties against right-handed batters – in other words, when they DO NOT have the platoon advantage. The second chart is going to be the reverse – the worst lefties when facing left-handed pitchers. Both charts sort by on-base plus slugging percentage allowed. You know all the chart abbreviations except, possibly, for "TB" – "Total Bases."
The most interesting thing for me is that three pitchers make both lists and we'll focus on each of them after the charts.
Lowest OPS allowed to right-handed hitters by left-handed pitchers (through July 28):
|12||Jorge De La Rosa(notes)||Col||180||44||4||16||39||0.684||67|
Highest OPS allowed to left-handed hitters by left-handed pitchers (through July 28):
The three pitchers on both lists are Romero, Harrison and Wilson.
Most importantly, there are sample size issues with the lefty-vs.-lefty list. So that means that the performance here can be random. As a check, let's look at the career numbers versus lefties for the three.
Romero: .817 OPS allowed to lefties
So Wilson we can safely say is a fluke. Harrison and Romero though have a problem. Both rely heavily on their change-up, which tends to be less effective against same-side hitters. So their repertoire is more limited when facing lefties.
Against Romero, especially, opposing managers should use a reverse platoon system. But of course they will not because going by the book allows you to lose quietly and going against it, even if you know the odds favor it, risks the loud loss that coaches/managers hate the most. Loud losses get them fired.
Generally speaking, I think it's wise to be a buyer when a lefty has poor stats against lefties but good ones against righties. I think that leaves room for profit. Remember, many left-handed hitters are psyched out against any lefty pitcher. So odds are decent that poor reverse platoon splits will, well, reverse themselves. So this type of split focus can be a sneaky way to find value.
The number one thing to look for in a lefty pitcher is their ability to limit the effectiveness of right-handed hitters. So the major takeaway from this week's research for me is that Wilson has left the tier of the good and is now in the "very good" group with a decent chance to end up great – for the balance of the year and going forward in 2012 and beyond. There's wind in his face playing in that park, for sure. But when you adjust for league and park factors, I'm quite confident that Wilson is a No. 1-level starter.
Michael Salfino writes and edits the SNYWhyGuys blog that projects player and team performance for New Yorkers. He's also a quantative sports analyst whose writing regularly appears in the Wall Street Journal.