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Who'll Have The Lowest ERA On The 2012 Diamondbacks?

We finish our survey of the individual player projections for the Diamondbacks in 2012, by looking at the pitching statistics. The team improved markedly last season, shaving more than an entire run off team ERA, going from 4.81 to 3.80, though the overall league figure also declined, by a much smaler amount (4.03 to 3.82). This was powered by both the rotation and the bullpen. Our starters' collective ERA, even with the struggles of Armando Galarraga, etc. went from 4.40 down to 3.84. But it was the relievers who showed the greatest improvement, slashing over two runs as their ERA went from 5.74 down to 3.71.

What are the projections for 2012?

As before, we've taken the five projection systems listed at, and averaged them out to provide a consensus that will hopefully end up being their collective "best guess." Here's the spreadsheet with detailed numbers for all systems. The table below is split up into starters and relievers, with each group ordered in ascending order of projected ERA for 2012.

Starter 2011 ERA
Ian Kennedy 2.88 3.43
Daniel Hudson 3.49 3.52
Trevor Cahill 4.16 3.88
Josh Collmenter 3.38 3.89
Joe Saunders 3.69 4.38
J.J. Putz 2.17 3.00
Takashi Saito 2.03 3.23
Brad Ziegler 2.16 3.47
Craig Breslow 3.79 3.76
Bryan Shaw 2.54 3.80
David Hernandez 3.38 3.80
Joe Paterson 2.91 3.81
Wade Miley 4.50 4.43

It's hard to come out with any kind of composite ERA, since it will all depend on a number of factors. Firstly, there's the question of innings pitched by each player, which will weight the eventual outcome. It seems unlikely that Joe Paterson will throw as many innings as David Hernandez, say. Additionally, I've only listed numbers for five members of the rotation and eight relievers - the seven who are on the Opening Day roster plus the DL'd Saito. Chances of us getting through 2012 with just those thirteen names is practically zero. Only one NL team used less than 21 hurlers last year, and even the Giants used 17.

However, for quick and dirty purposes, let's just assume the five starters pitch equally, and so do the eight relievers. That would work out at an average starter's ERA of 3.82, which is just about identical to the number posted in 2011. The bullpen also comes in at something close to its 2011 figure, with an average ERA across the eight of 3.66. Making that number err on the optimistic side in both categories is the likelihood that replacement pitchers will likely be worse, i.e. closer to replacement level. Hopefully, the apparent decent depth we possess should help protect us, and there should also be some Darwinism at work, with the better pitchers likely throwing more innings.

The starters' overall ERA remaining static is surprising, given that four of the five are projected to increase, by amounts ranging from 0.03 (Hudson) to 0.69 runs (Saunders). However, that would be countered by the absence of a back end to the Arizona rotation which was pretty terrible. The worst five by ERA (Wade Miley, Zach Duke, Armando Galarraga, Barry Enright and Jason Marquis) combined for 34 starts - basically, a entire pitcher - and an ERA in those games of 5.94. While most of the systems didn't come up with numbers for the likes of Patrick Corbin and Trevor Bauer, likely replacements in 2012, they should be considerably better than that.

On the individual basis, it's worth noting that the team collectively underperformed their FIP [Fielding Independent ERA] by 0.22, one of the higher numbers in the league, and an expected regression is reflected in the 2012 projections. Whether that comes true or not will depend on how much of last year's undercut was due to luck and how much of it was due to defense. It's quite possibly a mix of both, but as measured by UZR, the Diamondbacks' defense last season was #1 in all baseball. If that persists in 2012 - and the whole Parra/Kubel thing may play into this - it'd seem reasonable to expect our pitcher's ERA to again be helped by those behind them

Meanwhile, Saunders' ERA has consistently beaten FIP every year since 2007, by a margin of between 0.10 and 1.09 runs. Which suggests that either Joe has been incredibly lucky, or there's something about his pitching ability over the past four years which isn't accounted for in FIP. It's something 'skins looked at last August, and we're really no closer to any definitive answer now. I'm reminded of the famous aphorism, "The harder you work, the luckier you get," and also the physicist Niels Bohr, who kept a horseshoe over his desk, because it "will bring you good luck whether you believe in it or not." Whether you choose to believe in Joe Saunders is, of course, up to you...

Over on the bullpen side, regression is generally forecast, with Bryan Shaw and David Hernandez expected to be the biggest victims. I think there's a couple of reasons for this. With Shaw, you've got less than 30 innings of major-league work as a track record. and his overall minor-league numbers are not spectacular, with a 4.33 career ERA. However, the light-bulb seemed to turn on in 2011. For Hernandez, projections are likely skewed by the fact that most of his career innings are still as a starter, where he struggled. Over 109 innings out of the bullpen, his ERA is an excellent 3.22, and with an excellent strikeout rate, his FIP was actually below his 2011 ERA, at 2.94.

Ziegler's another interesting case. He has enjoyed sustained success, virtually since breaking in to the big leagues - he had a scoreless streak of 39 innings to open his career, and his career number still sits at 2.43, more than a run below what's expected. Again, FIP appears key; his career number is 3.38, virtually in line with projections. He doesn't strike out enough hitters - six per nine innings this far, while walking 3.5, and that's not a recipe for FIP success. However, both numbers went the right way last year, to 6.5 and 2.6 respectively, and if he can maintain that progress, he should be fine.

[Just to note the tendencies of the various systems again, Bill James is the most pitcher-friendly, projection an average ERA of 3.45 across the dozen players for whom all the systems provided numbers. MARCEL is next (3.64), with little to separate Rotochamp (3.72) and ZIPS (3.75). Steamer is easily the most pessimistic, with an average ERA of 4.05, which is about 17% higher than Bill James, so there is a fairly wide range of standards, even across a reasonably-significant number of players.]