I don't really know who to blame here, but I'm gonna go with the board losing faith with Mourinho.
Ed Woodward must have people who advise him, who must know football.
He sees Mourinho, somebody who wants to invest money in older players (Not saying this is totally a bad thing) and doesn't want to give players who the club see as the future chances.
I'd go as far as saying Ed is happy enough to spend money on the players Mourinho wants, but at a price they want to pay. At the end of the day, Toby has one year left on his contract before he has a £25m buyout clause. The reported figure they want right now is 65m, and he would have little resale value at this point.
Maguire on the other hand, I'd say Ed was willing to spend more on, but it seemed Leicester did not want to sell.
You have to think, would getting Toby win us the league? I really don't think so, we'd still need more. So why sign somebody with 3 or so good years in him when Maguire could do a similar job for 7 or so.
You have to just look at Mourinho to see the problems he causes.
He's isolated Martial and by the looks of it Pogba also. These are two players United want to build around, yet Mourinho have them wanting to leave. (Pogba may be speculation, but there seems to be to much of it in my opinion)
If I was a footballer, I'd look at how we play and United right now (If I wasn't a fan) wouldn't be high up on my list of places I'd prefer to go.
Mourinho just has a negative aura.
In pre season he did nothing but complain. He sits in press conferences questioning why anybody would want to watch friendlies. We may all think it, but he actually comes out and says it, it's pathetic. Same goes with his comments after the Sevilla match. Saying stuff he shouldn't.
I don't know what happens behind closed doors obviously, but if I was the board, I'd be sick of Mourinho. Last thing I'd want to do is invest big money on shorter type transfers.
Rant over (Yes I am in the, I don't want Mourinho as our manager corner
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