Pitching by the Numbers: From the left

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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