Looks can be deceiving. I haven't seen him coach or his teams play so I have no opinion on that. Underwood's teams at SFA passed the eye test. Someone like Dan Muller at ISU doesn't exactly pass the eye test. He may just have the right group of players w/the right chemistry.
Underwood's Adj D -
2013 SFA Austin (before Underwood took over) - 9
2014 (Underwood's 1st year) - 105
2015 - 98
2016 - 38
Also Underwood took over a team that was 70 per Kenpom and moved went from 70, 69, 51, and 41 his last year. Way different starting position to then Keatts at UNCW.