I think this has become an issue of Garcia vs Tosin in the matter, other reasons have come up because one has left and one hasn't.Matter of opinion. He did well in other years as well. He can't have done worse than Garcia did v Lyon and Leicester...if he'd been given a chance.
Well, Tosin wasn't good enough to play for us in any season, despite loan spells, meanwhile Garcia seemed to impress everyone coming right out of academy, carrying a La Masia product status. We have turned on Garcia because he wants to leave for Barcelona, but if so, there was one condition that his price was met, and Barça, who spend millions on other players, cannot spend 20m on him because they think they can bully us into selling for cheap? So be it, no deal. As for Tosin, I'm fairly sure the club wanted him to renew, then go on another loan, but he's 23, it's not what he wanted. He does not have any place in this squad, where John Stones, Dias, Laporte, Aké have all been bought in to care for defensive needs. If you think Tosin staying and getting a 'chance' at 23 in the odd cup game was going to prove worth it then you are simply wrong, he decided to move, somewhere he can start permanently not having to worry about his next loan. We can wish him well and move on.
I can totally understand people are upset that a boy who's a blue through and through basically has had to leave, but the circumstances have meant he has to think for his career unfortunately.
p.s. we can't base on could haves and would haves in football either, not how it works. Same as saying if we had Messi in our lineup we would have won CL ; )