Even reduced wages l, what's the point seriously. He's never going to have an impact from the bench.
With respect, you're missing the big picture here. This falls somewhat within my professional ballpark so I'll weigh in with what's obvious to a lot of people:
Just going by what's being reported:
Mata is being extended with reduced wages to keep him in the first team squad as a rotational player, think cup games and the odd moment when a game is over, or even as fresh legs when we play park the bus and we're getting nowhere. He's the most creative player we have outside of Bruno.
Mata is
MASSIVELY popular in the dressing room. He's a rolemodel of a professional and one of the players the coaching staff want the upcoming youngsters to learn from. Even if he doesn't play much, you see posts from our players on social media all the time celebrating Juan. Bruno Fernandes has been vocal about learning free kick technique from Mata. He's by far one of the most intelligent players we have with the ball. He's just gotten slow.
So in short there is a squad harmony aspect. Mata is being kept around because he has a invaluable mature influence on kids like Mason, Amad, Hannibal etc etc.
Secondarily it's about keeping resource people within the club and that's primarily the motivation behind wanting to keep him around. Good organizations keep good people, and they've identified Juan as someone they want to keep around in management and within the clubs hierarchy when he retires.
The club is wise to not opt to extend his contact, but offer a new one with reduced wages to reflect his role. The club is also wise to keep professional sportspeople who can make meaningful contributions to the club pyramid once they retire.
If Mata signs, I'll be absolutely buzzing.