Thursday, May 27, 2010

Regression to the Mean vs. Performance

If I offer too many caveats to my post from Tuesday, I'm going to have to re-write the entire thing.

After reading one of Noah's comments, though, I thought some clarification was necessary:
The math suggests to me that I might get as many WHIP and ERA points just by CC and Vazquez pitching to norms (because of their innings).
Rather than reinvent the wheel, let's look at what I wrote this winter about starter and reliever ERA/WHIP earnings.

Ten Most Expensive A.L. Starting Pitchers 2009
(w ERA/WHIP earnings)
#Player$Sal+/-$E$W$E+W
1CC Sabathia$34$31+3$5$7$11
2Roy Halladay$37$28+9$8$7$16
3Josh Beckett
$28$23+5$2$5$7
4James Shields$18$23-5$0$1$2
5Zack Greinke$44$21+23$11$9$20
6Felix Hernandez
$40$21+20$10$7$17
7Francisco Liriano
$1$20-19-$5-$4-$9
8John Lackey$18$20-1$2$2$4
9Scott Kazmir$9$20-11-$2-$1-$4
10A.J. Burnett$19$190$1-$1-$0

Average$25$23+2$3$3$6

Ten Most Expensive A.L. Relievers 2009
(w ERA/WHIP earnings)
#Player$Sal+/-$E$W$E+W
1Jon Papelbon$22$29-7$4$2$6
2Joe Nathan$28$26+1$4$4$8
3Joakim Soria$19$26-7$3$2$5
4Mariano Rivera$27$25+2$4$5$9
5Bobby Jenks$14$22-8$1$1$1
6Brian Fuentes$17$21-5$0-$0$0
7B.J. Ryan-$1$21-22-$1-$2-$3
8Kerry Wood$11$19-8-$0-$0-$0
9Joey Devine$18-18

10Frank Francisco$14$15-1$1$2$2

Average$15$22-7$2$1$3

These were the most expensive American League starters and relievers last year. The best starting pitchers were more reliable in ERA/WHIP. However, the $2 per pitcher earnings isn't as wide a gap as you might expect.

The other side of this proposition is that there were more relievers in the A.L. last year who earned $5 or more in ERA/WHIP than starters. Twenty relievers earned $5 or more, while 13 starters pulled off the trick.

It was easier last year to grab a quality ERA/WHIP reliever off of the waiver wire than a starting pitcher. Andrew Bailey, Matt Guerrier, Mike Wuertz, Darren O'Day, Jason Frasor, Sean White and Jose Mijares were all available in most American Leagues at some point last year. All earned $5 or more combined in ERA/WHIP.

Meanwhile, not a single American League free agent starter could pull off this feat. Brad Bergesen, at $3.91, was the top free agent American League starter in 2009.

In addition to the advice I already gave to Noah, add this piece of knowledge to the mix. Keeping your under performing starting pitchers in the hopes that they will improve is not a bad idea. Once you dip into the free agent pool, the best route to improve your ERA/WHIP is through middle relief. Picking up starting pitchers is not the quick route the ERA/WHIP salvation that many believe it is.

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