Why so sure about that? There wasn't a team playing worse basketball down the stretch than Penn State who were losers in 5 of their last 6.
BracketMatrix had IU as a 10 seed in 85 projected brackets. Teams behind IU were:
10 Texas Tech
11 Utah St (AQ-already won tournament)
11 Wichita State
11 ETSU (AQ-already won tournament)
11 Richmond
11 UCLA (play-in)
11 NC State (play-in)
12 Cincy
12 Yale (AQ-already in NCAAT)
12 Stephen F Austin (AQ)
12 Liberty (AQ)
Last 4 in were
Xavier
Texas
Stanford (lost opening round to Cal terrible loss)
Northern Iowa (lost in first round of conference tourney)
There would have had to been MASSIVE upsets for IU to not have made the tournament last year. Texas and Texas Tech was a likely a de-facto elimination game so that eliminates one bubble spot. Even if IU had loss to Penn State it still would have been a Q1 loss and nothing to significantly knock them out of the field.
There you go, stating facts and doing research. Interesting that it is crickets from those that say IU was on the bubble.