So what is the system they play
What does he deploy that stifles creativity
Does he tell guys not to be creative
JG and Tkachuk were creative as hell last year
It's a system that heavily prioritizes shot volume over shot quality, and simplicity/predictability over creativity. He's a coach that is risk averse and loves his "puck management".
Jarome Iginla saw a 30 point drop in production under Darryl directly after winning the Art Ross and Rocket, and remained a 70 point player until Darryl's departure. The season's following he scored 94, and 98, and 89 points respectively. Anze Kopitar saw a 40 point increase the season following Darryl's departure, and produced 92 points. Jonathan Huberdeau has gone from a 1.44 pts/g season to a 0.69 pts/g season. Elite talent has historically struggled under Darryl atleast from a statistical point of view. Now you can argue if what he demands from these players leads to more team success overall, but recent history suggests it doesn't. This is looking like the 4th time in his last 6 years as a head coach that he will miss the playoffs. This isn't a 3-2 league anymore, and the things that made his teams so successful over a decade ago seemingly no longer work. The game is simply far to reliant on skill these days, and he has shown little to no adaptability.
I do however think he was smart enough last year to simply let those guys go out and do their thing, but I don't think a whole lot goes into a decision like that. They were about as dominant of a trio as you could find in recent memory. He doesn't have the luxury to rely on them anymore, and it shows.