It is hard to argue with the above logic. I have been shocked by Bard's complete lack of velocity. I figured he could sit consistently around 95, but as you noted he's throwing considerably less than that. It's disappointing.
He has flashes of effectiveness, so I'm not entirely ready to give up on the project--particularly since I don't think DiceK or Cook are better options. Oswalt could be though.
Also, Bard seems to have particularly bad innings with walks, which tells me that the command issue is intermittent rather than constant. Lester had similar problems earlier in his career, though they weren't as bad.
All in all, if his velocity doesn't pick up he doesn't have the ace potential I thought he might. If his velocity exists only when he's in the pen, and the velocity is his standout attribute as a pitcher, then he should be in the pen.