I think it's reasonable to have concerns about his reluctance to rotate since Ajax fans, generally a knowledgeable bunch, also complained about it.
I think the amount of games Eriksen has played despite being over 30 with a heart condition is crazy.
The thing is he does actually rotate when he feels he has the players. I think you can now trust that Malacia, AWB, Garnacho and Fred have probably proven themselves to be proper rotation players for him. Maybe he is still unsure of the others, or has no hope for them and is waiting for able replacements. For instance I reckon if FDJ was, somehow, signed in the summer then he'd have no issue using Eriksen regularly in place of Bruno or FDJ.
What it seems more to me is that he likes having his first 11 to go out and do a good job and then use the lead to rotate. I suppose its up to our bench players to show him they can be trusted to start. I thought AWB was finished here but now reckon that ETH would have no problem starting him in games against mid-tier opposition even if Dalot is fit.
Not to say I always agree with him. I think Cas should never have played against Palace, for instance, but I guess his plan is that eventually the squad will be better and long term he won't have to play in that situation. Fans would have slated him if he started McTominay (Fred was also 1 yellow away from suspension) and we had lost the game.
On Eriksen, midfield is our biggest issue in terms of rotation. He trusts Fred and that's it I think. We have also lost DVB. Its why I really hope Hannibal and Mainoo can progress quickly (think they both have the talent) and perhaps become trusted options for next year. I think the plan was FDJ and Eriksen as a back up to him and Bruno but we missed out unfortunately.
With Wout in I reckon if Martial stays fit and Sancho comes back we'll see a lot more rotation in the front line too.