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Is the Diamondbacks bullpen overworked?

This was the line taken by Derrick Hall on the radio this morning, but there seems some question as to whether this is actually the case. I thought I'd pull some numbers and see whether there is objective evidence to back up the claim. After the jump, you'll hear what Hall had to say, and see what I found out...

Here are six ways to measure bullpen usage, along with the figures for Arizona, where they rank in the league, the NL average, and the low and high values for each metric.All numbers as of this morning].

Arizona Rank NL Avg Low High
Innings 146.1 8th 144 121.1 (CHC) 173 (FLA)
Batters 668 6th 638 546 (PIT) 782 (FLA)
Relief apps 153 3rd 143 126 (PIT) 164 (FLA)
0 days rest 30 14th 35 28 (SFG) 54 (WAS)
Outs/app 2.9 10th 3.0 2.7 (STL) 3.3 (HOU)
Pitches/app 16 14th 17 14 (STL) 19 (FLA)

Based on this, there really doesn't seem all that much to suggest that the bullpen - as a collective entity, at least - has been overworked. They have pitched almost exactly the same number of innings as the league mean, though have faced 30 batters more than average. This is probably largely a result of the struggles - when you give up hits and walks, that will lead to additional batters faced. I'd like to have been able to check the number of pitches thrown, but couldn't find splits for relievers by team on that.

However, in terms of the sheer number of relief appearances, the Diamondbacks have been pretty active. We average 3.26 relievers/game, trailing only the Marlins (3.42) and Nationals (3.50). On the other hand in some aspects the bullpen has been less stressed than most in the league. We have sent relievers out there in consecutive games [0 days rest] less often than almost every other team, and there's nothing to suggest that they are being asked to get any more outs, or throw more pitches, than other bullpens.

That, of course, doesn't mean that there are not individuals in the bullpen with whom we should be concerned. In order of innings pitched so far, here are the top five, along with what their pace is for the full season, and how many innings they threw last year.

Name 2009 Games + IP Pace 2008 Games + IP
Juan Gutierrez 22 - 26.1 76 - 90.2 25 - 138*
Esmerling Vasquez° 20 - 24.2 69 - 85 24 - 83*
Tony Peña 23 - 22.1 79 - 77 72 - 72.2
Chad Qualls 18 - 20.0 62 - 69 77 - 73.2
Jon Rauch 23 - 19.2 79 - 67.2 74 - 71.2
° - 2009 includes games in Reno.
* - worked mostly as a starter.

Chad Qualls is the one I am least concerned about. His pace numbers would actually be the lowest he has pitched, both for games and innings, since his rookie season of 2004. Tony Peña has averaged 73.5 games and 79 innings over the past two years, so his numbers too, don't look all that far away from the norm - perhaps a game more thus far than we'd expect. Rauch's stats are kinda off, skewed by appearance like Monday's, where he came in but didn't retire a batter. As a result, that innings pitched total would be a career low for a full season, but 79 games is close to his three-year average of 82 games. However, I do have to wonder if his heavy workoad is partly tied to his slump in some way.

It's probably our new arms, Juan Gutierrez and Esmerling Vasquez that concern me most. While neither should have issues with the innings, the switch from starter to relief, and the resultant tripling or more of appearances. It's one thing, such as Vasquez did last season, to throw eighty-plus innings with four days rest between trips to the mound. It's quite another to throw them, almost alternating days on and off for six months. The same goes for Gutierrez:, and it's also worth pointing out that no exclusively relief pitcher reached the ninety-innings mark last season, as he is currently on pace to do. And only four of the 347 in the majors reached 85 frames of work. So I wouldn't be surprised to see those two somewhat less often going forward. And here's the whole interview with Hall from KTAR this morning [I had to drop it down here to stop it from interfering with the photo]

Audio courtesy of KTAR 620