I think makeup is the key to the decision. I might actually ask who wants to volunteer for the role and whoever raises their hand give him the ball. It would not shock me if nobody raised their hand. Thats our problem.
Miller has HUGE issues with delivery. You can't be working on your delivery while also trying to close for the first time in Boston. Miller has also been used very seldom late in games. He only has 5 holds. And he seems fragile to me.
Uehara has closed in the past and I believe he didn't like it. He also failed in his playoff performances. Not sure he can handle the pressure. Not to mention the repeat outings. What if a player asks not to close?
The problem with a bull pen by committee is that EVERYBODY has to be able to handle the pressure. And because you never get an opportunity to get used to it, it makes the pressure even higher. This is not a long term option. For a week or two to figure out who can close, sure. Maybe even a good idea. Long term, no way.
Lets also not forget the Boston pressure is the most in baseball. It takes a special breed. Not sure who has it on the team. Agree though that we should try internal options first. Trading for a reliever is the last option and should occur in late July.
Although I would try Tazawa first, its fine to try Miller first. If his delivery is settled, it might work. Doubt it though.