That's a hard one to measure, and hard to say that the trade "bombed." Bledsoe won us a significant number of games on his own, and is the best QB the Bills have had since Kelly. NE got our 2003 first, which ended up being #14. They then traded that and their sixth to the Bears to move up to 13 and grab Ty Warren, who was a solid player for them for a few years. With #14 the Bears took DL Michael Haynes, who was a bust. Also worth noting that the Bears were only at #13 because they traded #3 to the Jets, so that they could move up and grab Dewayne Robertson (also a bit of a bust).
So yeah, the Pats definitely got a good player, but there's no telling that the Bills would've made the same moves if they'd been in that position. So I wouldn't say that the trade "bombed." Drew had us competitive in December, something you can't say about many recent Bills Quarterbacks.