Yeah he's rotating the defence fine IMO. I'm questioning why do Eriksen, Bruno and Rashford play almost every minute. Bruno has more minutes played across all competitions (not counting world cup) than De Gea for example, Eriksen is 3rd and Rashford is 4th for us. Eriksen visibly drops in the 2nd halves, so yes we need to sub him now (didn't happen in the first half of the season much, so very clearly that is the effect of tiredness). Players are more prone to injuries when they are fatigued. With Rashford, it's preventative if anything. We know he suffered from over playing in the past and it led to bigger injury problems and dramatic losses of form. Given we rely on him entirely for our attack, I'd just rather it doesn't happen but tbh I understand that one (though do think it's fine to take a risk vs fecking Reading and giving him a full week off).
With Bruno, well he's used to playing every minute so he's probably fine anyway. But again. Fatigue happens to all, and he plays every minute of every game basically, so taking the chance to rest him before the next month of games would've been wise IMO.