Bear in mind that 2019 IU has an inflated record due to weak OOC scheduling. 2019 IU shows up as an 8-5 team but they were only 5-4 in conference. If you add them up points-wise, they were dead even in margin of victory/loss throughout 9 conference games. In conference they scored 267 points, and gave up... 267 points.
I'm sure the weirdness of 2020 in general, and the fact that they only had 7 games prior to the bowl, also add up.
It's a lot more statistically common to go 6-1 (86%) in 7 consecutive hands of blackjack than it is to maintain an 86% win rate in 13 consecutive hands of blackjack. Give 2020 IU a full season, and maybe it would have smoothed that outlier nature a little more. Or maybe it wouldn't, if they scheduled OOC like they did in 2019 (Ball State, FCS Eastern Illinois, should-be-FCS UConn).