Everyone knows RPI means nothing.
To get into the at-large conversation you need to beat upper-echelon Power 5 teams. And then, avoid any embarrassing losses. That's it. Done.
A secondary option is to win 30 games. Something like 30-3, with a loss in your conference Championship, gets you in the at-large conversation. So, schedule a bunch of cupcakes, don't screw up in your conference season, and maybe some USA Today blogger will take up your cause and write a nice column about how you were snubbed.
A third option, completely out of the Zips control, is that the MAC as a whole ascends to a higher basketball level. With a couple juggernaut teams like the MVC has in Northern Iowa and Wichita State. Then you're in the conversation. But even then, you can get "Saint Mary'd" and miss the tourney.
We haven't won an NCAA tournament game of any kind since 2007, and we've have numerous opportunities against "meh" competition (UMass, Northwestern, ND, Ohio State-lite, IUPUI, UWGB, etc), so the "we got snubbed" cries ring pretty hollow to me. We just aren't good enough to merit consideration. We need to win our Tournament. Simple as that.