I'm a day late on this, but moving a guy out of the spot you promised him is embarrassing for him. The guy lobbied for the job (as anyone should, dedicated fellow that he is) and is pretty much going to get shamed out of it because of a skill set that should be apparent to his boss. Pillar doesn't need to be a meathead to take a confidence blow, but then again I don't know him and maybe he'd be unfazed.
My point is that if Gbby never gave him the job in the first place, the worst he'd have to deal with is a super quality CF lobbying for a promotion. Address it with "Look, we love you Kev, but the big bats need to be up there. It's always been like that." Sucks, but he can't argue with that. Now you risk embarrassing the guy (which I'm sure is a thing, because I've never had a job in which the media has been down my neck) as well as putting the team's overall performance at risk. This is all Gibby's fault. I'm sure there are a dozen guys in the locker room who are lobbying for something that shouldn't get, and it's the boss's job to say no.