I think sometimes fatigue created during T-A 2021 is severely overstated here. No doubt it may be a factor but how many riders are able to keep top form from Strade Bianche until Ronde van Vlaanderen? Because we saw a monster MVDP there and if it was any other rider we wouldn't have any doubt that he peaked too soon before the monuments.
He missed a big win after Tirreno that year but I wouldn't say he had a not good classics season after that.
In M-S-R he starts the Poggio in 29th position, is around 10th position when Alaphilippe attacks with Van Aert on his wheel and he is the one who closes the space. Right after that Van Aert attacks again and it goes until the top of the Poggio. Stuyven sneaks away in the descent and he has no team mate to close the gap while the group relies on him and Van Aert to close Stuyven. So I'd say there was more a matter of bad positioning and lack of team mates than of legs.
In E3 he is one of strongest in the race, attacking from far and manages to crack Van Aert with a crazy acceleration in one of the last bergs. The group regroups after that on the flat run-in and with their team advantage, Asgreen breaks away while he has no one there to close the gap (as far as I remember, Vermeersch rejoined the group after and he was alone with Senechal on the same group).
In RvV he also made a couple of very strong climbs who managed to crack Van Aert, but Asgreen was super and as VDP led much of the final 12 km flat run-in, Asgreen had more in the tank to be the faster in the sprint.