Except he's not getting short-changed this year. Not by any stretch of the imagination.
So... You know why players hate being tagged right? Long term security is valuable, and his bargaining power with the team that drafted him will never be higher unless he hits the open market, where he is likely to make more through a bidding process
Would you rather play on a one year contract for $10M and try to negotiate better after, or play on five year contract worth at least $10M a year? If you were worth at least $10M, does it not benefit your employee to get a contract for you now instead of when it comes time to negotiate next year? Like the process or not, it is good for both the team and the player to get this deal taken finalized now unless they plan to let him walk next year.