Quoting: justaBoss
I can credit Bowness for making Heiskanen look great defensively, but honestly he was already that by default. However, I will heavily criticize Bowness on hindering his offensive play. Overall I think he's hindering them over anything else.
As for Trotz, I mostly will credit him on building a defensive culture which can help D-men look great (at least those with some actual defensive capabilites). Those who live of offensive game will not look as good.
Will a D like Scott Mayfield who's no good offensively look great elsewhere or will he turn a Chiarot once he leaves? Who knows. Trotz system has created the value on the guy.
Mayfield is who he is - a good 3rd pair defensive D who can spot as a 2nd pair D. He's nothing special on a Trotz team, he'd have the same impact anywhere else in a 3rd pair role. If a team tries to play him in a top 4 role full time, then they'll regret it.
The narrative that Trotz makes defenseman look good or gets the most out of them is exaggerated because of how bad defensively as a TEAM they were in 17-18 under weight - but the forwards played a big role in that - Tavares, Bailey, Lee , Alan Quine were among the worst defensive forwards in the NHL. 17-18 also marked the year that Boychuk fell off a cliff, yet he was still used in a top pair role with Leddy.
What made the difference in Trotz's 1st year is that he gave Pelech + Pulock an increased role and didn't allow the forwards to cheat for offense. Mitch Korn worked his magic with the goaltenders which is one of the main reasons the isles had success that year. In Trotz's 4 years as HC he couldn't get Chara, Greene, Boychuk, or Leddy to have even an average defensive impact. If his system was that good at making D look better than they are, then it should at least make them serviceable. Which is why that narrative is BS, the players he had were just great players on their own.