Some writers grumbled why the White Sox quickly signed Jake Peavy to a new two-year contract.
Because, Peavy is a "quality" starter.
Stats guys believe a "quality" start is a pitcher throwing 6 innings and allowing 3 or fewer runs. However, critics believe that a 4.50 ERA is hardly a "quality" outing for a pitcher, even in the juiced ball era.
So what is a quality start? Is it total victories? Or is it keeping your team in the game with the opportunity to win? Is it shutting down your opponent to take the pressure off your offense? It is probably a combination of those factors.
The oldest markers of a good pitcher is earned runs and control (WHIP).
And baseball as a whole has some clear statistical benchmarks in ERA and WHIP.
In 2012, American League teams combined had an average ERA of 4.08.
In 2012, National League teams combined had an average ERA of 3.95. This probably is the differential of the NL not having a DH.
In 2012, all teams combined had an average ERA of 4.01. So one could argue that 4.00 is an "average" major league pitcher benchmark.
It is also confirmed by a means test. In 2012, 7 of the 14 AL teams had a team ERA under 4.00 while 7 of the AL teams had an ERA above 4.00. In the NL, 9 teams had team ERA under 4.00 while 7 teams were higher than 4.00.
Clearly, a "quality" start of 4.50 ERA is false, considering an "average" pitcher is significantly below that number at 4.00 (11.1 percent).
It may get subjective at this point, but one could argue that a "quality" pitcher has an ERA of 3.50 and an "excellent" pitcher has an ERA of 3.49 or below.
In conjunction with lower ERA is a lower WHIP (walks plus hits divided by innings pitched). In regard to both the AL and NL, in 2012 the average WHIP was identical at 1.31. This figure represents the average "control" a major league pitcher has on the mound. The lower the number, the more control. The higher the number, the less control (since walks is an equal component).
So how was Peavy's 2012 season? He had 32 starts, a 3.37 ERA and 1.10 WHIP. His ERA was 15.76 percent below the 4.00 standard. His WHIP was 16 percent below the 1.31 standard. You would have to put Peavy's season in the "excellent" category.
And that is why the White Sox signed Peavy to maintain an excellent one-two punch with starter Chris Sale (29 starts, 3.05 ERA, 1.14 WHIP) at the top of the 2013 rotation.
