First off, Boras is the attention whore who made the announcement. A-Rod's problem is letting Boras do it. I bet he's loving the abuse he's getting today for his agent's doings.
I can't believe how quickly some fans forget. The Sox didn't even make the playoffs last year. I'd be happy to have him around to make sure that doesn't happen again any time soon.
There's no way he makes 30M/yr. Remember when Damon had an offer for 7 years and Daisuke was worth 20M/yr on top of the posting fee? Don't buy the Boras hype.
A-Rod obviously just wanted out of NY. The most money was probably going to come from an extension with NY (with a 20-30M subsidy from Texas) and they didn't bother negotiating.
As for the Sox, I don't think anyone over 28 is worth a >5 year contract. Those are the kind of deals the Yankees have smartly gotten away from.
So I'd love A-Rod on the Sox for 4 years at 20M/yr. I'd settle for 5 years at 23/yr. Of course neither of those get it done.