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Sean Green Is At It Again

Memories of last year's horrific collapse will not soon be forgotten, and right in the middle of everything was a bullpen that started to struggle at the worst possible time. Sean Green was no exception; between August 5th and September 18th, he allowed 17 runs and 43 baserunners in 18.2 innings, tarnishing a strong campaign and playing a significant part in 2007's emphatic demise.

The same phenomenon looks to be repeating itself once more in 2008. In the month of August, Green's put 22 people on base in 9.1 innings, striking out just four batters over the same span and yielding an OBP of .449. Where earlier in the year he was one of the lone stable assets on the staff, recently he's been nothing short of an unpleasant adventure.

Here's what's most interesting to me, though - where it seems pretty easy to pinpoint exhaustion as the root cause behind Green's struggles (he's tied for the AL lead in appearances with 63), if he's tired, it's not showing up in his actual stuff. Check it out:

Speed pfx_x pfx_z
Fastball, Season 89.4 -10.4 -1.0
Fastball, Slump 89.7 -10.2 -0.3
Slurve, Season 76.0 5.8 0.3
Slurve, Slump 75.7 7.5 -0.7

Green's stuff has been pretty much of the same quality over this recent stretch as it has been all season. In fact, his breaking ball's actually been moving more.

The issue isn't with his stuff. It hasn't changed. And he's still been getting a bunch of groundballs, so it'd also be hard to argue that his results have been substantially different. No, the problem is this simple: since returning from his little break, Green hasn't been able to throw strikes. At all. His strike rate of 53% over the last few weeks is almost hilariously bad, well below his season rate of 61% (which is still pretty weak). Yeah, he's faced an inordinate number of lefties over that span, but he hasn't even been regularly finding the zone against righties.

Not throwing strikes is a great way to look like a bad pitcher. Well, no; not throwing strikes is a great way to be a bad pitcher. Which isn't to say that Sean Green is bad, but during August, he's been exactly that. What's curious to me is that his stuff has stayed about the same, which leads me to wonder about two things:

(1) Is he actually tired*, or is this just statistical noise?
(2) How does cumulative pitcher fatigue usually manifest itself - worse command, worse stuff, worse velocity, or some combination of the three?

#1 is something we'll just have to wait to find out. #2, meanwhile, seems like it'd be a fascinating area of research, although I imagine you'd run into a heck of a problem trying to come up with a data pool. How do you identify a pitcher who's worn down over the course of the season? Looking only at guys who're getting worse results is the nasty sort of selection bias, since it doesn't account for people who're pitching through fatigue effectively. I guess it's another one of those interesting ideas that's virtually impossible to investigate.

As far as Green's concerned, we can only hope that he's able to shake these struggles off, since he's a valuable component of the bullpen going forward. Personally, I'm not worried; he shook off similar struggles a year ago, and rosters expand in five days. But it'd be nice to see him get a couple strong outings under his belt before the end of the season. Just to be sure.

* as the life of the party he may simply be hungover all the time