I don't lose a lot of sleep over 5 year deals, especially for 28 year old left handed relievers. Yeah, by year 4 and year 5, he'll probably be overpaid, but lefty bullpen guys live in this league forever. Not having to give up the draft pick is gravy.
I lose a lot of sleep over 7-8 year deals for those over 30. Like, say, Ellsbury. As soon as someone else is ready, Yanks are going to give him away and have to pay the rest.
And if I were a Sox fan, I'd be very worried about David Price. He had great outings and not great outings. Too many not great outings for the ace he's paid to be. 2nd year is critical for him. But even if he returns to form, which is questionable at best, there's 5 more years at $32M per year. I don't think the Dodgers are going to throw them a lifeline this time.