He just looks like one of the many players in our squad who have some good traits in their game but, unfortunately, they don't make the cut at top level because their overall game has lots of weaknesses. Ander can press high, that's what he's basically good at, and he has an eye for late runs in the box. These two aspects of his game (press high on the pitch/goals from midfield) can make him an option for any manager but that's when the problems start. You play him as an #8 and his lack of organizing skills, his poor defensive contribution and his bad positioning create more minuses than the pluses he offers. You play him behind the forward and you can't expect double figures in goals and/or assists and exceptional play making abilities.
As things stand and with Pogba's transfer being imminent, i suspect that he will be an option for the #10 role under Mourinho. The captain will start, for better or worse, and when things aren't going well for him his immediate sub will probably be Mata. But if we're a goal up and the opponent has put some real pressure on us, then Herrera will be an option that will allow us to basically play with three central midfielders. As for a deeper role, he might get some time there but i don't see with whom he would create a well functioning partnership. Alongside Morgan there will be no creativity through the middle and alongside Carrick/Bastian there will be huge issues when we're defending off the ball. I leave the Pogba option out simply because in such a setup Herrera would have to be the one sitting deeper, something that at list in my eyes is not an option.
I was watching the game with some friends yesterday and one of them, who's a Liverpool fan, turned to me and said at halftime: "He's your Hendo, isn't he? He's good at one thing (he can press while Henderson has an eye for second balls) and he has the odd goal in him every now and then, like Henderson, but if you look beyond that, he doesn't really make any significant difference when he's playing". It was an observation that got me thinking tbh...