I wouldn't call it controversial but the whole "you wouldn't need to look at stats if you played the game" thing is pretty stupid because we have tons of examples of guys who "played the game" who made obviously stupid decisions that a bunch of stats hobbyists on twitter immediately recognized as terrible decisions. Marc Bergevin played the game and he thought Karl Alzner was a good investment. Dale Tallon played the game and he handed Vegas 2/3 of their top line for no reason, and signed Dave Bolland to a massive contract. Nonis and Chiarelli both played the game (NCAA, but if you're going to use your Junior B experience to say you played the game that counts too) and they did Clarkson/Lucic/Hall-Larsson.
It's not that you needed stats to realize Karl Alzner was cooked, but a cursory glance at possession metrics for 5 seconds would tell you it's absolutely insane to offer that player 5 years at 4.6M. Somehow nearly 1200 NHL games weren't enough experience for Marc Bergevin to realize that was a horrible idea like hundreds of random people on HF and twitter did, whether they looked at stats or not. There were still a lot of people who played the game and someone who makes a lot of money as a GM based on his experience playing the game who thought Alzner was worth that contract.
For my real controversial opinion it's probably removing offside. I could handle leaving in the blue line in terms of once the puck enters the zone you need to clear if it leaves the zone, but I don't think offside should be called on zone entries.