Going back to UMass, I too think this is a good move. UMass was actually a member of the MAC from 2012-2015, so they're probably familiar with how the conference runs.
I'm starting to notice a trend though. First Army to the AAC, now UMass to the MAC. Is there a reason why these independent schools are joining conferences? My gut feel is that it has something to do with media coverage or something along those lines. I doubt it's easy for crappy programs like UMass or UConn to make a lot of money with TV deals whenever they aren't affiliated with a conference. I think having exposure on ESPN with the MAC will create more $$$ for the school. Just my thoughts tho.