Hamonic is not wayyy better than a second pairing defenseman on a playoff team, albeit borderline playoff team. (When your goalie is your "playoff team", I don't put much stock into being a "playoff team")
With that said, Hamonic has the higher ceiling, the higher skillset, and the projection to be a first pairing d-man. To say the same about Mcdonaugh would be a little foolish at this point.
I disagree with this. The Rangers had a solid defense (better than it has been in probably a decade) this season and scored just enough goals to get in while battling a plethora of injuries (I believe they had three times as many man games lost as they did last season when they didn't make it). Hank had a great season but he didn't do it alone
I think McDonagh and Sauer where the X-factors that pushed the team over the playoff/no playoff line (just barely). Both led the Rangers in +/- ... McDonagh was a +16 in just 40 games and Sauer a +20 in 76. Both rookies playing 18-19 minutes a game
I'm not sure what kind of offense he'll be contributing in the future, but he's going to be a rock on defense (hell, he is already).