The defensive rankings reveal why he did so poorly. Most people just gloss over this but his one decent team was good defensively ranking 22nd. Just not a good teacher.
Some people may gloss over this while others, like you, have a single minded obsession (to the point of being a broken record) about this. Neither dimension is a magic bullet. Both are important but the more important one is not the one you think.
I ran a simple correlation of Big Ten team winning percentages against Offensive and Defensive Team Ratings for a five year period. For Offensive Ratings, the higher the score the higher the offensive rating. For Defensive Ratings, the lower the score the better the defensive rating so you would expect Offensive Rating to be positively correlated and the Defensive Rating to be negatively correlated and they are.
2021: OR: .872; DR: -.452
2020: OR: .851; DR: -.765
2019: OR: .805; DR: -.538
2018: OR: .746; DR: -.738
2017: OR: .711; DR: -.606
Both are strongly correlated with winning percentage but the Offensive Rating is higher in every year although they are about the same in 2018.
A few day ago you posted that you never have a problem admitting you're wrong. So, can you admit, given the data above, it's ridiculous to harp on the defensive dimension as being the savior while largely ignoring the more important offensive side of the court?
What's particularly interesting in the data above is that 2021 is the year where there is the biggest difference between the two. This was the year with the highest concentration of games to date being within the conference.