Masterson >>>>> Bard.
It. Is. Not. Close.
Masterson is a starter, or has the ability to be one. Bard does not.
To my view, an above average starter > a great reliever unless that reliever is currently an elite closer. If Masterson has the ceiling of a #2 starter, I consider that a higher ceiling than an elite setup man, which is the most you cn ask of Bard right now. So I say that as far as ceilings go, Bard's is flashier, but Masterson's is more useful to the team -- and anway, Masterson is closer to his ceiling at a younger age.
Masterson is the same age as Bard. He has been an effective starter. He has been an effective setup man. SOmeday, 2-3 years from now, Bard MIGHT be doing what Masterson did LAST YEAR.
I don't think you can just say that Bard has more potential than Masterson just because he throws 100 and was higher on the draft slot. What they've done in the meantime is a huge advantage for Masterson, ERA in 8 Portland starts notwithstanding. Besides that, Bard's ceiling has dropped since the draft thanks to his headcase fiasco in 2007, and Justin Masterson's has only gone up. since he was seen as a reliever on draft day and sbubsequently proved that he could start too.
Bard might have a plus-plus fastball because of velocity. Masterson's sinker is plus-plus too, because of its movement and his ability to command it. If you had to ask me point black which was a better main offering for a relief pitcher, I take Masterson's power sinker every day of the week and twice on Sunday's over a generic 100.
Think of it this way: Bard's job is to make sure you don't hit the ball. If you hit it, he's already failed in his primary objective as a pitcher. Masterson's job as a power sinkerballer is to make sure that even if you do hit it, it's on his terms. Even if you make contact you haven't necessarily beaten him. That's a more complete strategy.