Excellent article as usual, I'll add some thoughts myself.
I married into a UW family, so I follow their sports teams pretty closely, seen him play a ton through the years, screamed NHL player from the start. I was totally shocked wasn't drafted earlier because he has size, strength and great finish around the net.
I think Blake is spot on with the Holmstrom comp. with some slight differences. As the gif shows, that is something Mersch does frequently, an amazing ability to bring the puck off the boards and into a high scoring area, either by carrying it or passing it and getting to the front. I think he skates better than Holmstrom does, but isn't quite the pure unmoveable ox that Holmstrom was. Holmstrom was perhaps the best shot deflector I've ever seen, don't really know how great Mersch will be, that's a talent you pick up on after watching a player play well over a seasons worth of games. Where he is similar is being a great garbage man like Holmstrom was. Mersch not only has great hands around the net but also knows how to find the space needed to get that extra split second.
I remember them playing NoDak a few years ago and Mersch completely dominated his current teammate Derek Forbort, remember thinking to myself should I be happy that the Kings were able to get this guy with a 4th rounder or sad they took the defenseman with a 1st rounder.