Who Should Start Game Four for the Phillies?

Philadelphia Phillies skipper Charlie Manuel is expected to decide soon that Roy Oswalt will be the fourth starter for the club heading into the postseason. The decision obviously would come at the expense of 23-year-old standout Vance Worley, whose rookie season has made some folks in the City of Brotherly Love wonder if he’s the real fourth ace in this star-laden rotation.

Certainly, Manuel’s decision would have been expected in April when the Phillies entered the season with Roy Halladay, Cliff Lee, Cole Hamels and Oswalt on staff; but a flurry of ineffective starts — and two trips to the disabled list — have marred Oswalt’s season. Worley, meanwhile, now looks like the guy who should have been manning that fourth spot all along. His ERA is 3.00 — compared with Oswalt’s 3.66 — and Worley’s defense-neutral estimators all are about a third of a run better than Oswalt’s, as well.

So should Oswalt really be such a lock for that start? Well, here’s the way to tell: Tell both pitchers to warm up, and then put the radar gun on the 34-year-old’s fastball. If it’s above 91.5 mph, put in Oswalt. If it’s below — well, you know the answer.

Below is FanGraphs’ plot of velocity by start for Oswalt. Note that these charts don’t include his Sept. 12 start (91.87mph) and his Sept. 17 (91.85mph), which are a small decrease from the last start pictured, on Sept. 7 (92.18mph).

Notice that I’ve drawn a thick red line down the center at 91.5 mph, dividing his starts into games when he had his fastball velocity working and games when he didn’t. This red line represents the difference in between the fourth ace that the Phillies thought that they had all along and the below-average pitcher who has been bested by a bespectacled rookie. The ace Oswalt gives up half as many runs and strikes out 50% more hitters — while the other Oswalt has a strikeout rate that would rest somewhere between Livan Hernandez and John Lannan on the National League’s K% leaderboards.

Velocity

GS

IP

ERA

SIERA

91.59-93.04

8

52

2.25

3.32

89.85-91.44

13

73.1

4.66

4.29

While ERA can be a useful tool to evaluate pitchers, it struggles when dealing with small sample sizes. Because of that, I dug deeper to confirm my suspicions. I broke down Oswalt’s performance into buckets — shown above by thinner black lines on opposite sides of the thick red line, representing at 92 mph and 91 mph — to see how his peripherals and his SIERA moved with his velocity. In fact, Oswalt’s SIERA is more than run lower when he’s at his best, thanks to a strikeout rate almost double that of his inferior alter ego.

Velocity

GS

IP

ERA

SIERA

K%

BB%

GB%

Over 92.0mph

4

27

1.67

3.26

22.0%

7.3%

52.7%

91.5-92.0mph

4

25

2.88

3.40

17.3%

3.9%

49.3%

91.0-91.5mph

6

29.1

5.22

4.31

12.7%

5.2%

39.6%

Under 91.0mph

7

44

4.30

4.29

13.4%

5.7%

41.3%

Deciding between Oswalt and Worley isn’t really that hard because Manuel doesn’t have to choose between two similarly competent pitchers. Rather, he’d be choosing among two of three possible pitchers who show up in the bullpen: Worley, Good Oswalt or Bad Oswalt. Fortunately for the Phillies, the difference between Good Oswalt and Bad Oswalt is easy to root out. Charlie Manuel just needs to bring his radar gun.



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Matt writes for FanGraphs and The Hardball Times, and models arbitration salaries for MLB Trade Rumors. Follow him on Twitter @Matt_Swa.



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BDF
Guest
BDF

Fantastic. I’ve been imagining that “What Do Advanced Stats Have To Tell Us About Charlie Manuel’s Game 4 Starter Decision?” would be my first article if I were fortunate enough to be selected as Fangraphs’ new writer, with the thesis that there would be anything. This isn’t exactly advanced stats, but it is advanced analysis, and it’s great.

Although, the bullpen performance of a pitcher, especially a veteran like Oswalt, I think is not strongly correlated to game performance. Bouton has a great section on this lack of correlation in Ball Four. So maybe Manuel should go Koufax/Drysdale and start Oswalt and have Worley on the verge of warming up if it looks like Roy-O doesn’t have it.

Thanks, Matt.

Yirmiyahu
Member
Yirmiyahu

So Oswalt pitches better on days when he has his good stuff. I’m guessing, if you did this same study with any power pitcher, you’d get similar results.

jorgath
Guest
jorgath

While true, Oswalt is one of a “type” of pitcher wherein there is a much greater difference between “good Oswalt” and “bad Oswalt.” I’m guessing that if you did this same study with another power pitcher (if someone wants to try, I suggest Verlander) that yes, you’d see a dropoff on days when his pitches aren’t as good, but the quality difference wouldn’t be as severe as it is for Oswalt.

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