Best way to play defense is to always play on offense. I'm thinking that's what McIlvane made the switch and lean into Luneau's forte, which is being an OFD. Because
@mightyquack has often shared that Luneau's defense is behind development. Also, the Gulls really needed to add more offense.
McIlvane had Helleson last year and the start of this year, but Helleson was never able to establish himself in the AHL b/c he was, I'm guessing here, being groomed into a #1D type defenseman who can play offense and defense. That isn't Helleson's game. Once Helleson got to the NHL and just played his game, which is a shutdown D who can chip in here and there, then his talent flourished.