Erm, Pogba isn't inexperienced at all, mate. He's a 24 year old French International who's played in Champion's League Finals, won Serie A multiple times and been capped 44 times by his country.
Pogba is a highly talented, but mentally weak player under pressure and has disappeared against Liverpool totally, and Chelsea too in a crucial match. And that's just what comes to mind immediately.
His decision making, and ability level drop significantly when it most matters.
He isn't like Rooney at 18 - 20, he doesn't have that 'refuse to lose even you're 3-0 down' mentality, and to suggest he does is an insult to Rooney.
Speaking of which, Rooney at 24 was what we should be aspiring to. Pogba, while a different type of player, and a good one, isn't half the player that Rooney was at that age.
And no-one was gibbering on about Rooney 'needing time' when he was 24, because he didn't need any excuses.
Ronaldo at 24 I'll not even bother going into.