The Arizona bullpen in 2008 was a contradiction in terms. They posted a very credible ERA of 4.09, exactly on the NL average - and so rather better by the time we take park factors into consideration. But they had an abysmal 17-28 record, easily the worst in the league, so it seems the issue was not so much the number of runs allowed, as when they were given up. For example, our relievers could have proved thoroughly adept at shutting down the opposition when we were six runs ahead (or behind), but been a lot less successful at doing the same in tied games.

There'll be some significant reinvention necessary, with the departure of original closer Brandon Lyon and Juan Cruz. The latter has perhaps been the best bullpen arm over the past couple of years, but the impact of his loss is perhaps mitigated by Cruz's odd pattern of use: 69 of his appearances over the past two years have been in games the team was losing, compared to only 30 in which we were leading. Reinforcements have arrived in the shape of Scott Schoeneweis and Tom Gordon, though the latter is still some way off being ready. At the time of writing, the final couple of spots left in the 'pen remain to be decided, but I think we're largely talking blowout innings there. Here are the projections for the main five men: Yusmeiro Petit was already covered in the rotation. I've not included any W-L totals, since for relievers these are almost impossible to come up with, and are largely meaningless in any case.

Closer. Chad Qualls
2008: 2.81 ERA, 1.07 WHIP
Bill James: 3.51 ERA, 1.22 WHIP
CHONE: 3.73 ERA, 1.29 WHIP
Marcel: 3.66 ERA, 1.26 WHIP
ZIPS: 3.74 ERA, 1.30 WHIP

Despite some hiccups in the middle dealing with inherited runners, Qualls started and finished the season well, not allowing an earned run in April or September, and taking over the closer's role. It's not something with which he has huge experience - only eight career saves pre-replacing Lyon - and seeing how he responds to the inevitable blown chances will go a long way to deciding his long-term suitability. The projection systems all expect a regression to the mean, which is reasonable, but the only realistic estimate of saves is from Bill James, who predicts 33, which sounds about right.
AZ SnakePit: 3.55 ERA, 1.24 WHIP, 35 saves.

Set-up #1: Tony Peña
2008: 4.33 ERA, 1.33 WHIP
Bill James: 3.60 ERA, 1.23 WHIP
CHONE: 3.84 ERA, 1.31 WHIP
Marcel: 3.92 ERA, 1.29 WHIP
ZIPS: 3.71 ERA, 1.26 WHIP

While 4.33 is still a good ERA, it had to be disappointing for Peña, after an excellent 2007 (3.27 ERA). Batters simply hit him more often (.281 vs. .207) and his line-drive percentage rocketed from 11% to 20%, though he was the victim of a hefty .323 BABIP - league average was .300. That should drop a bit this season, but I'm surprised how much better some of the systems think he'll be - Josh Byrnes wants him to use his change-up more, which could help. However, he is still relatively young, having turned 27 in January, and his walk and home-run rates went the right direction in 2008.
AZ SnakePit: 4.00 ERA, 1.30 WHIP

Set-up #2: Jon Rauch
2008: 4.14 ERA, 1.19 WHIP [with Washington and Arizona]
Bill James: 3.55 ERA, 1.20 WHIP
CHONE: 3.91 ERA, 1.28 WHIP
Marcel: 3.92 ERA, 1.26 WHIP
ZIPS: 4.23 ERA, 1.28 WHIP
The 2008 number conceals how rank Rauch was for us: 6.56, with a .303 opp. BA, and six losses in barely a month - if we'd won just half of those, the D-backs would have taken the division. Whatever the reason [and a sick wife may be involved], we simply cannot afford a repeat this year, and outside of ZIPS, the expectation is he will do better. Diamondbacks' fans will probably need some convincing, and even if he pitches lights-out, it may be well into the season before that sinking feeling, all too familiar from when the tattooed giant pitched in 2008, starts to subside.
AZ SnakePit: 4.20 ERA, 1.29 ERA

LOOGy: Scott Schoeneweis
2008: 3.34 ERA, 1.38 WHIP [with New York Mets]
Bill James: 4.94 ERA, 1.53 WHIP
CHONE: 5.06 ERA, 1.60 WHIP
Marcel: 4.42 ERA, 1.44 WHIP
ZIPS: 4.67 ERA, 1.52 WHIP

Scott's numbers gets hammered by most of the system, but the key here is how he's used. If he's wielded as a blunt instrument by Bob Melvin, abandoned to face left- and right-handed batters with equal abandon, then an ERA of above five is not unlikely. But southpaws have really struggled against him, with an opp. OPS of only .520 and .556 the past two seasons - keep him for use in such situations, and the numbers will be a great deal better. My projection gives Melvin the benefit of the doubt, and assumes Schoeneweis will be handled correctly.
AZ SnakePit: 3.80 ERA, 1.37 WHIP

TBD: Tom Gordon
2008: 5.16 ERA, 1.62 [with Phillies]
Bill James: 3.60 ERA, 1.26 WHIP
CHONE: 5.23 ERA, 1.58 WHIP
Marcel: 4.60 ERA, 1.48 WHIP
ZIPS: 5.79 ERA, 1.59 WHIP
"I now have an idea what it's like to not have pain or soreness," he said - that's a good sign, and he's due to throw his first bullpen tomorrow. However, he has pitched less than seventy innings over the last two years combined, and was below league-average both seasons. The team won't be hurrying him back - not least because his cost is based on active roster time - but  at age 41, it's hard to see Gordon ever doing much of real value again.
AZ SnakePit: 5.33 ERA, 1.55 WHIP