Tuesday, February 01, 2011

Red Sox Bullpen Outlook

After yesterday's discussion of Rafael Soriano and Mariano Rivera, I figured I'd devote some time today to their significantly cooler rivals to the north. Unfortunately, today's write-up contains none of the intriguing organizational quabbling. Everyone in Boston's front-office is saying, at least publicly, how excited they are for the upcoming season. Other than a series of freak injuries to star players, the biggest problem they had last year was their bullpen. They were 12th in the AL in bullpen ERA, and their relievers allowed more home runs than any other team. This was despite the fact that their (unfairly) maligned starting rotation was 3rd in the league in innings pitched.

As the Red Sox prepare to retool for the '11 season, take a look at these three players:

Player A74.7295630767855
Player B67.0287728765956
Player C52.7231318617020

For a further breakdown, check out their per-batter splits:

Player A 9.833 3.88249.1673.7825.364
Player B 10.250 3.77641.0004.8645.125
Player C 12.833 3.78777.0003.30011.550

Player C was clearly the most outstanding when he pitched, right? Sure, he pitched the fewest innings, so you might not say the most "valuable." But, all else being equal, you'd want him, right? At least, you wouldn't cut him, right? Players A and B don't look too shabby either. Player B has the better ground ball percentage, so I'd take him. Plugging those three guys into an equation, assuming average defense, Player A comes out with a 3.33 expected Runs Against Average (exRAA), Player B with a 3.76, and Player C with a 3.04.

If you hadn't yet figured it out, player A is Daniel Bard. Player B is Jonathan Papelbon. Player C is Bobby Jenks.

Papelbon had a rough year last year as the Sox closer, while Bard was the hotshot rookie. Meanwhile, out in Chicago, Bobby Jenks was so inconsistent that he was non-tendered by the White Sox. This little exercise is meant to show the difficulty in evaluating relievers by runs allowed or ERA over only a 50-70 innings sample. In 2010, Papelbon allowed about 6 more runs than you would expect, based on the rest of his stats. Jenks, about 10 runs more, giving him one of the highest discrepancies between exRAA and RAA in the league. Bard, on the flip side allowed about 10 fewer runs than he should have expected. Simply stated, Bard was one of the luckiest pitchers in the league last year, Jenks one of the most unlucky.
Jenks gave up a lot of runs last year because he gave up too many hits. Yet, every indicator other than that showed that he was still outstanding, no matter what Ozzie Guillen's son thinks. Bard, meanwhile, got lucky for the exact opposite reason - lots of balls in play turning to outs. He pitched well, yes, but another sub 2.00 ERA shouldn't be expected. And Papelbon, the nominal closer - well, you can see why the Red Sox were willing to offer him. An ace reliever simply can't be giving up a homer once every 41 batters. I'd like to say it was a fluke, but his indicators were falling in 2009. Interstingly, Papelbon was pretty much hit-neutral. Those extra runs weren't from extra hits falling in, but from bad timing. His situational stats were poor, leading to a slightly higher than expected RAA.

That's not to say that Papelbon shouldn't be the "closer" in 2010. If the Red Sox are using their third best reliever to hold leads 4-1 leads in the 9th inning, while Francona is able to use Bard and Jenks in higher leverage situations, they are all the better. If Papelbon has another season of decline though, it will be hard for the Red Sox to refuse the calls to give the money job to Bard or Jenks.

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