It's always very tough to break through as a club like us and as heavy the responsibility is, there couldn't be a better chance for him to show what he can do. He has shown promises, we can only hope.
I think with the right setup he will be fine. Everyone thought McNair was gonna be bullied by Lukaku.
Yup, knowing Mourinho, he won't let Tuanzebe left isolated and exposed.
I have to disagree with the other posters though, but I understand the worry. True, now maybe not the ideal time to "blood him in" since we're chasing top 4 and winning the Europa League, but do we even have much of a choice at CB.
Our only choices are Bailly and Blind. Both can't play all the remaining games and have to be rested too for freshness. Plus, in case injuries happen to them, then we need a good cover who is available, good fitness and can do the job. This is where Tuanzebe comes in. It's important to give him gaming times to be ready and more familiar with the team and its setup. He's a natural CB.
Alternatively, Carrick could play there, but last time he did, I have anxiety plus he's better as CDM and we need him there. Darmian and Shaw is better at FB. Fellaini is an option too, but I won't risk it. Pretty much I don't trust any of them to play at CB, especially in dealing with crosses and quality attackers. At least Blind have a season dealing with those as a CB and did his best. The set-up by LVG helps Blind a lot too.
I think Mourinho sees TFM more of a midfielder and RB now, prolly as CB cover too after Tuanzebe. Even if Rojo, Jones and Smalling managed to return on time, their fitness is a big concern. In addition, Tuanzebe even Jose admitted have good defending qualities, so it's better to gamble on an inexperienced natural CB than those who aren't a natural at that position. The rewards are plenty than otherwise. Provided of course if Tuanzebe perform well in trainings convincing enough to play. Nervy in matches is normal.
So, for me, it is the right time.