Butch Jones was bad at Tennessee. That's no secret. Tennessee routinely underperformed in a conference that has declined a bit from where they were a decade ago, and in a division that has been one of the worst divisions in college football. An anonymous SEC coach commented on the job Jones did at UT in the 2018 edition of Lindy's college football preview magazine:
The comments are pretty funny, but it does come across as a bit unnecessary as Jones is no longer with the program, and hasn't been for months now. You also have to wonder whether the comments would have been as strong if he wasn't speaking anonymously.
Nevertheless, safe to say that his description of Jones' time at UT is pretty accurate.