When Nylander held out with his negotiation with Dubas. When he came back he looked like ass for the entire season. He scored 7 goals in 54 games.
That's a fair-ish example, although "entire season" is incorrect. In the last 35 games, he had 6 goals and 24 points. I wouldn't call that ass. However, in the first 19 games he had 3 points averaging 2 minutes less/game than Dach is this season.
Not that "19 games" should be the magical number, but this can't continue for the entire season with Dach.
Andrei Svechnikov tore his ACL causing him to miss 33 games+playoffs but was still excellent in his next season. Now if the argument is that missing 80 games is far more impactful than the amount Svechnikov lost, you also have to consider how it took Svech closer to the start of next season to be able to train properly.
Hertl also had an excellent following season when he missed half a season with the same injury as Dach.