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Pitching by the Numbers: From the left

Michael Salfino
Yahoo Sports

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):

Rank Name Team AB H HR BB SO OPS TB
1 Jonny Venters(notes) Atl 148 25 0 21 41 0.472 29
2 Cole Hamels(notes) Phi 414 83 5 23 106 0.541 121
3 Clayton Kershaw(notes) LAD 435 98 8 28 128 0.591 138
4 Ricky Romero(notes) Tor 367 78 9 31 93 0.614 122
5 CC Sabathia(notes) NYY 474 116 5 36 99 0.622 154
6 Cory Luebke(notes) SD 165 34 6 12 47 0.628 61
7 C.J. Wilson(notes) Tex 440 100 7 36 103 0.635 151
8 Matt Harrison(notes) Tex 352 83 7 31 55 0.639 120
9 Erik Bedard(notes) Sea 245 54 8 19 63 0.648 91
10 Gio Gonzalez(notes) Oak 365 83 7 45 90 0.653 121
11 Cliff Lee(notes) Phi 420 106 10 28 117 0.679 160
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):

Rank Name Team AB H HR BB SO OPS TB
1 J.A. Happ(notes) Hou 81 24 2 11 19 0.866 40
2 Jo-Jo Reyes(notes) Tor 126 40 2 10 19 0.834 58
3 Matt Harrison Tex 116 34 4 8 25 0.81 54
4 Ricky Romero Tor 160 43 4 24 33 0.793 67
5 John Danks(notes) CWS 119 35 5 8 17 0.787 54
6 Bruce Chen(notes) KC 78 23 2 10 12 0.768 31
7 Brett Anderson(notes) Oak 109 33 4 3 17 0.761 46
8 C.J. Wilson Tex 116 31 2 14 32 0.744 45
9 Hisanori Takahashi(notes) LAA 80 22 2 7 16 0.73 32
10 Jason Vargas(notes) Sea 125 34 3 8 18 0.711 50
11 Tim Collins(notes) KC 79 17 2 19 20 0.705 27
12 Randy Wolf(notes) Mil 100 25 1 10 24 0.702 36

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

Harrison: .785

Wilson: .566

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.

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