Theres two things at work here.
1) The 3 line transition occurred through Tippett, the moment Kane got here. I state this because other posters (not you) in a months time will be attributing this quantum change to Woodcroft. The transtion to 3 lines should not hamper your top stars production too much, because it actually opens up increasing shifts where opponent has trouble coming up with line matching, or has to spread their coverage. McDrai production wise would benefit in that scenario, even with somewhat reduced minutes.
2)Blanket adherence to schemes among ALL players can limit the peak production of generational talents. Its the primary reason Tippett had come in here and said that he would greenlight McDrai. That they would be allowed to continue to play aggressively forward, and that their offensive instincts would not be curtailed. This is not a solo thing. Deboers and other coaches believe in the same. That these are the two players you allow to cheat forward, same way Gretz was always allowed to. Woodcroft from my understanding isn't that way. He wants all players coming back in NZ, and being numbers back. Its possible under Woodcroft that deep forward and Jump D gets somewhat curtailed. I mean theres still some confusion in it to be expected but the last 3 games I've seen Drai be hesitant on the rush. My belief is that McDrai are better as free agent players using their offensive instincts.
This leads me to the last thought that constant flux can exist in how players would play naturally, than in very scheme enhanced play. I think this can often confuse players as it becomes contrasting instinct vs "oh this is what I'm supposed to do" As others have mentioned non stellar players like Foegele or Ryan benefit more from enhanced structure. Its not as clear that superstars do.
Agree on Point 1 which I'll call BK and PK ... before Kane and Post Kane
. This player finally enabled reasonable depth to roll out the 3C spine which Tippet did immediately. I'm glad Woodcroft has carried that through and feel he has deployed the forward lines and d-corp very well. Resetting McDavid and Puljujarvi moving up Hyman creates a strong two way top line. Draisaitl gets a big, physical volume shooter in Kane to help carry some physical load. Yamamoto gives a high work rate but production better fit on a good team's third line but in Edmonton's shallow depth he's tied to Draisaitl. Nugent Hopkins gets an erratic Foegele whose better set as a third line winger and some face-off/defensive support via a patch fix in Ryan. Cycling through top six players to give quality running mates for McLeod and Benson is smart.
About Point 2, we're four games into the regime change so I think it's too early to project what Woodcroft will do with his personnel deployment. This team has reset its work rate and simplifying its structure and building consistent execution has to help this team. I don't think it will sacrifice this team's offensive instincts let alone its two super elites. These are all elite level players who have played variations on systems play throughout their development. Heck Nugent Hopkins has had 8 variations of the theme with 8 NHL turnstile coaches. Players adapt through deeply learned experience.
We've seen on the PP flatlining that team's adjust to tendencies of this team and its two elites. I don't think McDavid or Draisaitl's high processor instincts will be inhibited with system tweaks that require structure and accountability across all zones on the ice. They think this game at a rare elite level that will always seem instinctual in exploiting weakness. Grez was other worldly in regular season play in a different era. But when required the Oil playoff machine learned to close out low scoring games.
Regarding your examples of Foegele and Ryan, the former is finally fit into a 3W spot where his speed and forecheck can be asset rather than a top six role where his hands and average processor are exposed. Ryan's game from Calgary days has dropped off but plug in as a utility winger with Nugent Hopkins who is hot returning from injury and Ryan is starting to look like a serviceable player again. They need that strong structure because their games are limited that elites who's processors and skills are on a different level. Woodcroft's deployment of the D has been fantastic.
This team is four games in. Lots of runway to see how Woodcroft rolls his lines and usage. I like what I've seen so far.
