I disagree.
I don't think there was a substantial difference between what Tubby accomplished overall, vs what Richard accomplished. It is not "absurd" as you stated. Far from it.
The difference in the Big 10 schedule alone could knock Tubby down a few percentage points and elevate Richard a couple in terms of overall winning percentage
Factoring going to the postseason is a totally different argument, but I would say between the two again very comparable, in my opinion.
Tubby - 3 NCAAs, 1 victory plus 2 NITs (1 runner-up) over 6 seasons.
Richard - 2 NCAAs, 1 victory plus an NIT Championship over 7 seasons.
I have no problem with stating Tubby accomplished more, but I think it was extremely marginal. If one places more value on the 2016-17 season in which they finished 4th under Richard and got a Bye into the Big 10 Tourney, it's totally reasonable to say it's a dead heat (or nearly).
Tubby never had a team that got a Bye in the Big 10 Tournament. Never.