A year or two ago he was playing a different role, in a different style of team. That team had horrible imbalances in its setup. You can't expect a sitting CM to dominate when you had an incredibly imbalanced defence that chopped and changed every week. One week its Smalling/Jones, then Bailey/Rojo, then Jones/Rojo etc etc etc. Then we were needing to rest Shaw/Valencia/Young every other game, it was horrible.
Right now he's coming off recovering from two fairly bad injuries, not rest. He's normally a fully-fit player and cruises through games and he's proving that now by playing every 3 days. Back to your original point, he's not getting any younger, surely if he was too old, his legs would be gone now? Why is he controlling games?
When you've got a well-drilled balanced team, you need a Matic in there to knit it all together, he's a top-class midfielder and he played a large part in Chelseas title winning team. Probably the most underrated player in this current United side, I found it strange you'd just write him off because he's in his 30s.
He's a big part of why we're passing forward quickly. He's always looking forward, for Pogba or Bruno, or Mason - see our third goal.
I knew his form in his last half season with Arsenal was poor but I just thought it was because he checked off and not interested to play for them again, and I think many also thought the same. The scenario of the signing, us hijacking the deal from City, the piano video introduction. This was just a great pleasure for me at this time. It was great fun, up till he started playing. Never ever expected it to to go this route by the end of it for him. Expected at least 1 great year from him or something. Oh well.