Last season, Javy Guerra was one of the Dodgers' few real bright spots aside from Matt Kemp and Clayton Kershaw. Pressed into the closer's role because of Jonathan Broxton's implosion, Guerra finished his rookie campaign with 21 saves and a 2.31 ERA, and entered this season as the club's incumbent closer.
In his last five outings, Guerra has blown two saves, suffered one loss in a non-save situation, and allowed two runs in the ninth inning in another outing, a game he entered with a tie score.
"I said all along that I didn't want to have to do this, but I didn't want to be hardheaded either," Mattingly said. "It's kind of like guys that I think can hit lefties, but if they don't the game tells me they're not doing it. With Javy, the game's really making the decision for me."
Jansen, meanwhile, has a 2.70 ERA, and is tied for the major league lead with 16 games pitched. Jansen's 27 strikeouts, in 16 2/3 innings, are the most by a reliever in baseball.
Funny thing is, Guerra really hasn't pitched all that badly. He's got a better strikeout-to-walk ratio than last year, and he hasn't given up a home run. But he has given up 16 hits (many of them ill-timed) in a dozen-plus innings.
There's really no reason to think Guerra's become a different, worse pitcher. There's also really no reason to think Jansen's not a better pitcher. Since first reaching the majors in 2010, Jansen's posted a 2.22 ERA and struck out 15.4 batters per nine innings.
And yes: 15.4 is a lot of batters.