I don't think Holl has forgotten anything, he never really knew what he was doing in the first place.
It was the same story the last two seasons, Justin Holl would play a very simplified, defense first game where he wouldn't try to carry the puck at all and he would actually look competent due to his deference to Muzzin and Muzzin's strong play. Inevitably, after about 20 games of success with this style he would revert to trying to go on rushes, looking off easy breakout passes to Matthews/Marner etc. to try and go end to end and his true colours would once again show.
No, but seriously, I know a few of us have noticed that he can't make good passes under pressure and that he loses track of his man in the D zone for a couple of years now, he has been my least favourite Leaf since signing that contract extension. He has been somewhat of a Dubas pet project for about 5 years now so unfortunately I think our management has some blind loyalty to him. Try as I might, I try to see the good in him that other people claim to see but I just can't, his decision making is just so poor in multiple aspects.