The only problem I have with these types of deals is that the player will always earn more than they should. Sign for a few years that you grow into, then you sign your next deal that overpays early again for you to grow into it, etc. Perhaps they'll be a bargain by the end of the deal, but what about the years leading up to the end of the deal? I'm using hypotheticals now, but if a player signs for 5 years that turns out to be a bargain in the last year or 2, it doesn't change the fact that he was overpaid for the majority of the contract.
In Tatar's case, I don't think that is a big issue though as even if he is overpaid for the entire thing, a 3-year, $2.75M contract is not going to cause any issues. It's the long-term, high dollar contracts that suck.