I think people like to gloss over the health aspect of these post TJS.If he was healthy, he would probably be getting a 1 year deal worth between $13M-$17M, so to have him in your system for 2 full years to work with your pitching staff, and possibly get him back for part of this season not for much more money, I don’t really see it as an overpay.
Maybe 80-90% make it back to pitching, and a subset of those are not quite the same.
More likely than not Sandoval will be back to his previous self (whatever that is), but I don't think it should be compensated as if it's a given. Wait and see approach is better unless you're getting a huge discount.