One statistician: Peavy's ERA would be around 4.00 with White Sox
If San Diego ace Jake Peavy eventually relents and joins the White Sox, don't expect him to contribute his customary sub-3.00 ERA.
In fact, Sox fans ought to be content if the 2007 National League Cy Young Award winner maintains an ERA under 4.00.
That's according to Evanston resident Dave Studenmund, the primary owner of The Hardball Times Web site that's one of the sport's leading lights for statistical analysis.
Studenmund bases his thumbnail projection on two factors: Peavy's potential switch from the National to the American League - and from the majors' most repressive run environment to one of its most liberal.
"Pretty clearly, the American League is a tougher league," Studenmund said. "I've read several studies that say for pitchers, (the league change) will add a half-run to your ERA.
"And people don't realize what an incredible pitcher's park Petco is and what a great hitter's park Comiskey is."
According to Baseball-Reference.com's park factors, Petco Park games have produced just 89 percent of the runs of a normal National League contest over the last three years.
Peavy's statistics reflect this spread. Since Petco opened in 2004, the 27-year-old right-hander has delivered a 2.71 ERA at home and a 3.37 ERA elsewhere.
U.S. Cellular Field, meanwhile, has generated 105 percent of the runs of a normal American League game over the last three years.
That's partially due to U.S. Cellular's tendency to serve as a launching pad, but at least Peavy appears to be neutral when it comes to giving up fly balls. Since 2004, his groundball ratio has been 43.2 percent.
"If he were a strong flyball pitcher, then (a trade to the White Sox) would be a problem," Studenmund said. "He's obviously a great pitcher, even if you knock out (the) Petco (effect), but expect an ERA of 4.00 in a good season."
Peavy predictor?
If you go to Baseball-Reference.com, you discover Josh Beckett owns the second-best similarity score to Jake Peavy in baseball history.
Coincidentally Beckett, who's one year older than Peavy, can offer everyone an idea of what happens when a blue-chip right-hander goes from the National League to the American League - and from a pitcher's park to a hitter's park:
TEAM SEASONS IP W-L ERA ERA-Plus**
Florida 2001-05 609.0 41-34 3.46 118
Boston 2006-09 627.3 52-30 4.25 111
** - ERA-Plus measures a pitcher's ERA relative to his league and takes into account park factors, i.e. whether his home field is better for producing or preventing runs. An ERA-Plus of 100 is considered league-average.