Yes he is, and was Oscar better than Mata, mourinho thought so.
Who says no other clubs are interested though?
As for why the teams I listed he'd be an improvement for, United wouldn't sell to them I'd hazard a guess, certainly not Liverpool, and spurs have about thirty million centre miss already, loch did try to get him when he left saints though in preference to wanyama which shows his thinking.
Oh yeah mourinho also rated a broken down falcao and 37yo drogba ahead of lukaku, managers make strange decisions.