The team dramatically underperformed last year, so it's reasonable to assume that a fair amount of those wins are made up with average performances across the board (JFaS posted in another thread what the projections for our team are for next season with replacement level players at 2nd, catcher, and SP, and I believe it was something like 86 games).
Replacing JPA with Hanigan should be a cheap improvement at catcher and wouldn't likely cost a top prospect. There's been some talk that Porcello might be easily obtainable (Detroit needs bullpen help and we're overloaded there). He'd provide us with solid innings and definitely has some big upside if things click. That would leave us with 2b and one SP. There's a number of trade candidates for 2b that should come fairly cheap, and we should have enough money remaining to fill the final SP slot from FA.