Why Pelfrey went to the splitter

Mike Pelfrey added a split-finger fastball to his repertoire for the 2010 season, and we’ll see it in a regular-season game for the first time tonight.

Why did Pelfrey feel he needed a split-finger fastball at this point in his career? A check of the numbers on Fangraphs.com gives us some indication:

Pelfrey threw a fastball that averaged 92.6 miles-per-hour last season. That’s hard enough to land on the first page of most leader boards involving starting pitching. But it’s not something that has produced success.

Pelfrey threw his fastball 78.3 percent of the time last year, which actually was less often than he threw it in 2009 (81.2 percent). Of the 130 pitchers who threw at least 100 innings last season, Pelfrey’s rate ranked as the second-highest in the majors behind Rockies starter Aaron Cook.

The problem for Pelfrey is that he wasn’t fooling anyone. Fangraphs tracks data that allows you to tell how frequently hitters miss on swings at pitches out of the strike zone.

Pelfrey ranked second in that stat too -- second-worst -- at 23.2 percent (by comparison, Johan Santana rated among the best in the majors at 37.5 percent). Pelfrey used to be good, by this stat’s standards, at getting hitters to miss out of the strike zone. But his number dropped nine percent from 2008 to 2009.

The other interesting thing to notice is essentially a coincidence, but it’s noteworthy nonetheless.

Fangraphs has three other pitchers listed as averaging 92.6 miles-per-hour last season. They are:

Brett Anderson, who closed 2009 with a 4-1 record and 2.20 ERA in his last five starts.

Matt Cain, who was 14-8 last season, and ranked seventh in the National League with a 2.89 ERA.

And Roy Halladay, who many think is the best pitcher in baseball.

Pelfrey’s ERA in his last 11 starts last season: 5.56. That’s not up to the standard that the other three pitchers who match his pitch speed have set.

Time to worry?

Should Mets fans be concerned with losing two out of three to start the season? Well, that depends.

If you’re someone who thinks that it’s going to take 90+ wins to win the NL East, you have reason to be a little nervous.

The Mets have had 10 seasons in which they’ve won at least 90 games. In nine of those 10, they won at least two out of three to start the season. The lone year in which they started 1-2 and won 90+ was 1990, and that year, it took the firing of Davey Johnson to turn the season around.

In fairness, the Mets have had good seasons in which they’ve started 1-2, most notably 1989 (87-75) and 1997 (88-74), but there’s a lot more bad than good here, most recently the stretch from 2002 to 2004. Those three teams all started 1-2. None of those seasons was worth remembering.