I have tried to do a little research- Note that Wichita State's RPI dropped to 46 after they lost to UNI today. I cannot find a single instance where an MVC ever got an at-large bid with an RPI worse than about 40.
Missouri State failed to get a bid in 2006 with an RPI of 21- which is still the record for best RPI team not to land an at-large bid since the RPI was invented 35 years ago.
It is rare for any midmajor to get an at-large bid with an RPI below 40.
So it all comes down to how many bids go to undeserving teams that upset someone and win their conference tournaments.
By the way- Evansville pulled away and lead by as much as 30 points before settling for a 68-42 win over Indiana State-
http://espn.go.com/ncb/boxscore?gameId=400870043
This might hurt the attendance a little tomorrow, but it will be UNI vs. Evansville for the MVC Championship-
https://twitter.com/MVCsports/status/706287731970736128