Myers got toasted on that play for sure, but I was half-watching the game replay on MSG and was wondering if he perhaps sold out hard on an aggressive attempt to stop the play at the wall knowing Leopold had the center of the ice? Pure speculation and I don't necessarily put much stock in it, but I could see that being the case.
Under those circumstances it is acceptable to get toasted, so long as the decision to attempt that is acceptable. Whether that was the case or not, the actual attempt should have had more success; with Myers' footspeed and reach, all it takes is a solid angle to cut the ideal lane away. In either case Leopold should have been able to stop Marchand or at least harass him more. He did limit Marchand's options enough that Miller never ever should have given Marchand that obvious backhand across the crease. So there's plenty of blame to go around there. I don't want to sound like I'm bending over backwards to think up ways to defend Myers, because usually I'm quite critical of him, I just think it might be a viable explanation in this particular case.
The pairing is just bad for business. I don't think either guy knows what his role in the pairing should be. Not every pairing has clearly delineated roles, but they seem to be confused in communication, awareness of each other, and they further seem to cramp each other's style. Some of their lowlights look just plain silly because of the finish, with weak, desperate closeouts, but the real breakdowns tend to happen seconds before from bad spacing.