I don't think that they'd "tear apart most of the inside players in Division 2," at least in Canada. I can only speak for Canada but the step from DIII to II is pretty huge and the gap between the top and bottom of the division are also very steep. There are lots of NT and U21 players running around the second division, and I know I've faced off against a number of big men better than those two this season.
Since there are more teams in the US I assume it's even higher in quality. They're definitely nice players, probably starters in USA II, and way better than the guys I am throwing out there on a regular basis, but I don't think they'd dominate. That said, they both have room for improvement and Mendez in particular is young with crazy potential, so he is only going to get better. What a fantastic prospect.