I'd take him. Tommy John was bound to happen eventually and that isn't a death sentence now adays and his hand injury was a freak accident (line drive) this year. I'd take him at a reduced price for sure.
If we lose Stone, that would be a huge loss. As annoying as he can be on twitter, and not calling out Larussa, he is one of the best in the business when it comes to talking logically about the game of baseball.
I absolutely would make that deal, especially if Jerry would pony up an extension (he won't). However, I agree that they will be able to top that elsewhere.
I'd gladly give him the 15 AAV. Prior to this injury I was all on board at 20-25 AAV. I'd still be on board with 15 AAV. A big discount for his shoulder injury and a year off seems reasonable.