Yeah those numbers aren't the greatest. But it's no surprise skill players perform better with skill players. Even McDavids numbers take a hit without Nurse, albeit not as much.
Tbh, He's always been decent goal scorer from the back end and improves year to year. Just by the eye test you can tell he's worked on his shot and mechanics; that Winnipeg goal were he changed the angle and picked a corner being a good example. His offensive reads and improvement on his shot look like a repeatable skill to me and he could very well continue to put up good goal totals.
Even if he has worked on his shot, defenseman can't shoot at 12.33% 5on5 for long periods of time. 2019-2020 regular season highest sh% from defenseman that played over 1000 mins (99 Dmen) 5on5 was 9.21. 10th highest was 6.67. 50th had 4.00.
And I don't put the blame only Nurse for those ugly numbers without McDavid, because the bottom6 posts that kind of numbers across the board. But he can't inflate those numbers and I think that elite players are always able to make players around them better. If you pay someone 9mil and he can't dominate the game without McDavid, he simply doens't deserve the 9mil.
Nurse&Draisaitl without McDavid post numbers in 49-50 range.
Nurse&RNH without McDavid post numbers in 43-30 range (really small sample size though)
McDavid&Bear without Nurse post numbers in 60-80 range (xG% 76, high danger cf% 83.33. But again a really small sample size and there is no way they could keep that rate up.)
McDavid&Jones without Nurse post numbers in 55-60 range.
It is pretty clear that McDavid doens't need Nurse to be best player in the world. But Nurse needs McDavid to have elite numbers.
Edit. I don't know if you saw my post a were a pointed out his shooting percentages. Before this year he had scored 25 goals even strentgh in 350 games. Now he has 10 in 34. Career sh% is 4.6 and is rocking now 12 this year. No way in million years that is repeatable.