I'm assuming that proving oneself means playing at a certain level. Schoop was still a below average player in 2015, does that count as having proven himself? I certainly don't think post 2016 Schoop signs that deal.
I think he's going to be a ~3 win player. I'd be fine with that on a playoff team.
Of course one of the underused advantages of signing a player to this type of contract is that if he ends up as even a 2 win guy you have a lot of excessive value if you want to flip him.
I get what you are saying but at this level of compensation the player doesn't have to be all that skilled to be worth it. As I said earlier this is pretty much the money Schoop has made over the same period of time.
I think a fair bit of it is a marketing problem. I think baseball as a whole has been very poor in this regard and have allowed the individual teams to conduct themselves without an overriding plan.