There's been some conversation in the comment section from Monday's Mug about the value of Jeff Suppan and how/if he should be utilized. At present, he's pretty much penciled in for a rotation spot in 2009, and likely will be even if the Brewers sign another starter, with Seth McClung getting bumped to the bullpen instead.

So the question becomes: What should the Brewers do with Jeff Suppan?

Step 1: The Trends

Suppan will be 34 by Opening Day, so it's likely he's in the decline of his career anyway, but these numbers would suggest he started his decline early:

ERA:
2005: 3.57
2006: 4.12
2007: 4.62
2008: 4.96

FIP:
2005: 4.53
2006: 4.70
2007: 4.42
2008: 5.51

WHIP:
2005: 1.38
2006: 1.45
2007: 1.50
2008: 1.54

Opponent Average:
2005: .273
2006: .279
2007: .294
2008: .292

WPA:
2005: 1.47
2006: 0.72
2007: -0.70
2008: -1.34

Sorry to bury you in stats there, click here for a definition of FIP and here for a definition of WPA.

Or, if you feel like you're missing the point, here's the summarized version: Suppan has been getting hit harder and giving up more baserunners each of the last four seasons. His FIP would suggest his excellent 2005 season was aided by luck, but would also suggest he could feasibly have been much worse in 2008.

Step 2: The Projections:

Despite what may seem like obvious trends in the other direction, both Marcel and Bill James have Suppan bouncing back in 2009:

Marcel: 169 IP, 4.82 ERA (4.81 FIP), 1.51 WHIP, .287 Opp. AVG
Bill James: 184 IP, 4.70 ERA (4.79 FIP), 1.45 WHIP, .283 Opp. AVG

Sean Smith's CHONE projections and Dan Szymborski's ZiPS paint a less optimistic picture:

CHONE: 161 IP, 5.31 ERA, 1.58 WHIP, .288 Opp. AVG*
ZiPS: 168 IP, 5.04 ERA, 1.52 WHIP, .280 Opp. AVG*

* - CHONE and ZiPS both did not include WHIP or Opp. AVG in their projections, but I calculated it from the data given.

The projections leave a pretty broad spectrum in which Suppan could perform in 2009, but even the worst of them (CHONE) projects at one run better than replacement level for 2009.

Step 3: The Alternative

Seth McClung started 12 games in 2008, and posted a 4.24 ERA and 1.36 WHIP in 63.2 innings. All told, he's made 44 starts over the last four seasons for Tampa and Milwaukee, and in his career as a starter he's posted a 5.70 ERA in 259 innings.

As a reliever, McClung posted a 3.67 ERA in 42 innings in 2008, and has posted a 5.19 ERA in 87 relief appearances.

Here are McClung's 2009 projections:

Bill James: 85 IP, 4.69 ERA (4.85 FIP), 1.53 WHIP, .253 Opp. AVG
Marcel: 89 IP, 4.35 ERA (4.49 FIP), 1.45 WHIP, .253 Opp. AVG
CHONE: 68 IP, 3.97 ERA, 1.57 WHIP, .230 Opp. AVG*
ZiPS: 90 IP, 4.80 ERA, 1.63 WHIP, .242 Opp. AVG*

*-See above.

All four of those projections have McClung pitching primarily as a reliever, and I'm not sure how the projections would change if he were seen as a starter, but I would guess that:

A) His ERA would likely go up as his innings increased, simply because his 2008 and career ERAs as a starter both are significantly higher, and
B) It's unlikely anyone would project him to pitch more than 150-160 innings, as he's never spent a full season as a starter.

For the sake of this conversation, I calculated McClung's ERA jump as a starter to be .54, which is halfway between his 2008 jump (.57) and his career jump (.51). It's possible he wouldn't experience such a severe difference in a full season as a starter, but his partial seasons as a starter are the only actual evidence we have to work with here.

With that change in place, here are Jeff Suppan and Seth McClung's average projections for 2009:

Suppan: 170.5 innings, 4.97 ERA
McClung: 150-160 innings, 4.99 ERA

Step 4: The Options

Obviously, if the season started today and the current roster stayed in place this debate would be moot, as Suppan and McClung would both be needed in the starting rotation. All scenarios considered from this point forward assume the Brewers will acquire another starter before Opening Day.

Option A: Send Jeff Suppan to the bullpen to start the season and give McClung the final spot in the rotation.

In the rotation: Assuming he adjusts well to being a full-time starter, McClung could be a noted improvement here. If he can pitch somewhere halfway between his projected numbers as a reliever and the somewhat gloomy projection I posted above, he could post an ERA of about 4.73 in 150-160 innings, an improvement of somewhere between 4 and 5 runs over the course of the season, or an extra half win or so.

In the bullpen: It's hard to imagine Suppan playing a pivotal role in the bullpen, both as someone who was just ejected from the rotation for ineffectiveness and someone who's only pitched in relief 16 times in 14 major league seasons. At most, he likely would pitch on occasions where a starter left early, or in the final few innings of 10-2 losses, or as the last man out of the bullpen in extra inning games. His contribution to the team would be negligible at best, as nearly all of his outings would be in exceptionally low leverage situations.

Option B: Suppan stays in the rotation, McClung stays in the bullpen.

In the rotation: Suppan will need to be kept on a short leash, and his short outings will cost the Brewers occasional runs and force them to overextend the bullpen from time to time. All told, he costs the team the above mentioned 4 to 5 runs that could have been gained by starting McClung.

In the bullpen: McClung is part of the conversation to determine a closer. Even if he doesn't win that role, he'll likely be used in high leverage situations (tied or leading late). If he can live up to his projections here (somewhere between 4 and 4.40, depending on who you ask), he could be worth a win or more over the course of a 70-80 inning season.

Part 5: Conclusion

I don't think any of us are really excited about what Jeff Suppan brings to the table for 2009, especially considering we're paying for fancy imported cheese and getting off-brand American. With that said, Suppan's projections for 2009 would suggest he's close to being able to reliably fill the role as fifth starter if used appropriately and watched closely, and allowing him to do so would leave Seth McClung in a position to contribute in a role which he may be better suited for. And if Suppan can't live up to his projections, the Brewers will know where to find McClung around May 1.

Resources used:

McClung's FanGraphs page
McClung's BR Page
Suppan's FanGraphs Page
Suppan's BR Page
Brewers 2009 CHONE Projections
Brewers 2009 ZiPS