If you actually think thats what I was saying you're either being deliberately obtuse to win an argument, or you genuinely don't understand the concept of space and movement in football. When Mata comes inside, he draws players with him, which allows Valencia space to bomb down the wing and get a cross in. It also means there's another body in the box ready to recieve the return ball (see the Valencia cut-back that he controlled and then rolled into Rooney in the first half). That kind of positional freedom also means he can draw players away from the likes of Ibrahimovic and Rooney, or get into space himself in dangerous positions to receive a pass from one of them. And if you think that's also just a form of getting out of the way for better players, you're being naive. It's a very subtle skill, and not that many players can do it effectively. The reason you didn't see that enough last season had a lot to do with Van Gaal's rigid positioning of players, but he was doing plenty of it in his first year with us.
By the way: "his stats are good but he doesn't contribute enough" is a bad argument that doesn't make much sense. And I think if you think about it, you'll find there aren't many #10's in the world that score as many goals or are as good at finishing as he is. Case in point: last season he scored more goals than James Rodriguez, David Silva, Christian Eriksen, Philippe Coutinho, Ivan Rakitic, and a bunch of others I haven't thought of... and that was from the right wing. In fact, the only #10 in the world with stats that genuinely shit on Mata's is a bloke called Henrikh Mkhitaryan. Hang on, that name seems strangely familiar...