Pitching by the Numbers: Half-baked notion

We like stories and second-half splits tell us one: pitchers are good early in the year but tire late. They fade.


Give me last year's trailers in ERA and WHIP during the second half and I will certainly find examples that seem to support this theory. If you are so inclined, you will bet against them. Except that when you look at three-year splits, you find what you'd expect to find if second-half (or post-All Star) splits meant nothing – the bad second-half pitchers are mostly the bad overall pitchers and vice versa.
Some people even bet that pitchers who improved last year in the second half will improve this year, too. I'm not sure what the story even is there. Okay, they don't tire. But how can they get better as the season wears on?
Let's illustrate with leaders and trailers, post-All-Star break from 2009-2011 (minimum 200 second-half innings pitched). We'll start with leaders first, even though, again, what's the theory here even? I'm not sure. If you are a believer, please share in the comments or tweet me @MichaelSalfino.

Player

W

IP

H

BB

K

ERA

WHIP

Clayton Kershaw

17

266

198

82

271

2.1

1.05

Felix Hernandez

22

315.67

267

87

279

2.54

1.12

Roy Halladay

26

309

289

47

275

2.59

1.09

Daniel Hudson

16

207

169

53

164

2.7

1.07

Chris Carpenter

24

327

295

74

246

2.72

1.13

Cliff Lee

22

299.67

277

35

283

2.85

1.04

Wandy Rodriguez

16

275.33

235

87

272

2.88

1.17

C.J. Wilson

16

217.33

179

85

229

2.9

1.21

Tim Lincecum

18

287

234

103

300

2.92

1.17

Hiroki Kuroda

16

244.67

215

50

204

2.98

1.08

Matt Cain

15

298

232

76

239

3.02

1.03

Ted Lilly

16

240.33

176

61

231

3.03

0.99

Justin Verlander

28

326.67

276

83

332

3.09

1.1

CC Sabathia

26

300

284

88

299

3.15

1.24

Cole Hamels

13

276.33

234

67

260

3.16

1.09

Zack Greinke

20

300.33

266

92

295

3.18

1.19

Tim Hudson

18

251.33

233

70

187

3.22

1.21

R.A. Dickey

9

212.33

202

50

116

3.31

1.19

Tommy Hanson

10

213.67

184

59

193

3.37

1.14

Roy Oswalt

15

221.33

213

47

175

3.38

1.17


Just a bunch of good pitchers. If second-half stats were not arbitrary endpoints, wouldn't you expect to see some pitchers who just got better in the second half? Maybe you say, "Well, no, because it doesn't make sense to get better as the season gets longer; only worse." More on that later. But for now, let's just dismiss the notion of better second-half splits for, say, last season having any predictive value.
And if you're still holding on to the notion that some pitchers on this list have pitched better in the second half than in the first, drop it. Look, if we were to stipulate that second-half performance is totally arbitrary and we merely have to look at the quality of the pitcher over the biggest relevant sample size to project him, we would still expect some variance. We certainly would not expect identical performance for first half during the period and second half, right?
Now on to the second-half trailers from 2009-11 (three years). Are they mostly the bad pitchers, period?

Player

W

IP

H

BB

K

ERA

WHIP

Homer Bailey

16

233

241

79

200

4.25

1.37

Bud Norris

14

220

221

97

206

4.3

1.45

Trevor Cahill

17

262.67

271

97

154

4.35

1.4

Bruce Chen

15

225

236

76

147

4.4

1.39

Josh Beckett

16

255.33

262

65

246

4.41

1.28

Yovani Gallardo

18

234.33

226

81

262

4.42

1.31

Derek Holland

15

204.33

201

73

179

4.45

1.34

Roberto Hernandez

11

243

269

85

153

4.52

1.46

Carl Pavano

16

286.67

348

54

165

4.52

1.4

Tommy Hunter

19

251.33

273

59

132

4.62

1.32

Brett Cecil

13

210.33

228

71

140

4.62

1.42

James Shields

19

284.33

305

82

243

4.65

1.36

Mike Pelfrey

10

257.67

293

87

142

4.79

1.47

Derek Lowe

18

236

296

72

172

4.88

1.56

Jeff Niemann

17

228

229

72

192

4.89

1.32

Livan Hernandez

11

231

266

70

126

5.03

1.45

Ricky Nolasco

16

221

242

49

214

5.05

1.32

Jason Hammel

10

234.33

261

71

179

5.11

1.42

Paul Maholm

6

206

262

54

121

5.24

1.53

A.J. Burnett

11

249.33

282

107

231

5.56

1.56


Mostly, yes. Remember, Roberto Hernandez is Fausto Carmona. Also remember that Hammel was bad, period, until this year. Okay, Cahill is up about a run higher but he's a young pitcher and you can understand why guys prior to their mid-20s may not have fully developed man strength/stamina. For those who say, "Young pitchers present risk that they may fade as the season wears on," I can't argue. Gallardo also was 25 or under for the period. The Mets Jonathan Niese doesn't make the list, but same story with him (though this is his age 25 season, were we should stop worrying, generally). Shields and Beckett could definitely fit the story that they just get tired in the second half. But then why are their strikeout rates steady? Shields is off more than a run though. But last year, his second-half ERA was 3.35, lower than this first-half ERA for the period. Either way, I'm not going to hang an entire theory of projecting pitching performance on the thin reed of James Shields.
I provide this information because people want it and am doing so in a manner that I hope dissuades you from making transactions based on it. In fact, I encourage you to take advantage of your leaguemates who may overreact to the second-half meme. There are profits there to be made – with the possible caveat pricing more risk into younger, generally less physically developed hurlers.

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