They say you can never have too much pitching.  But that’s apparently not the case for the Detroit Tigers.

Offseason wheeling-and-dealing deposited a number of new arms into the organization.  However, it looks like — despite injuries to Bobby Seay and Zach Miner and two rotation spots yet to fill — the Tigers still don’t have enough work for all of them.

That’s why it should come as no surprise that Jon Morosi of Fox Sports is reporting that Detroit is trying to shop lefty Nate Robertson.

Coming off an elbow injury, Robertson has made the adjustment from a left-handed power pitcher to a ‘crafty’ location expert a-la-Kenny Rogers.  But Robertson’s performance in Spring Training, which has been surprisingly effective, probably isn’t the reason he’s on the outside of the rotation looking in.

Why is that?  Dontrelle Willis.

D-Train, lampooned since 2008 for being one of the highest-paid benchwarmers in Tigers history, has been an even more surprising this spring posting a 1.20 ERA in 15 innings of work.  His walks remain a bit of an issue, but overall his command has improved and he appears to be pitching effectively enough to keep him a legitimate contender for the rotation.

So, in the end this probably comes down to salary and trade-ability.  Let’s face it, neither Robertson or Willis, who will make $25 million in 2010 between the pair, are particularly mouthwatering to any General Managers in need of pitching.  But given Dontrelle’s prior skittishness and Robertson’s comparative dependability, Dave Dombrowski probably sees Robertson as the only movable object.  With the pen already over-crowded and Robertson’s less-than-lights out stats as a reliever in 2009 (7.48 ERA in 22  games), there isn’t really anywhere for him to go.

It also stands to reason that the Tigers would much rather try to salvage as much out of the $15 million they’re paying Willis this season, knowing full well that they would likely not even be offered a rosin bag and a case of nacho cheese in a trade in exchange for him.

But dumping Robertson, in which case Detroit would definitely be on the hook for a big chunk of his salary, might prove to be a risky move considering Dontrelle’s history of falling apart.

Is saving at best a couple million worth the risk of having to plug a hole in the rotation with minor league duct tape? Or, does Eddie Bonine provide the Tigers with enough potential starting pitching insurance to make a trade more palatable?