His best years were 1998-2001 with the NCAA runs and that one 1st place tie which also coincided with a run by Texas Tech titles and NCAA runs so Marsha Sharp won it in 1998 and 1999. The Big 12 award is voted at the end of conference regular season before the NCAA's and most of Bill's best years have been good NCAA run years and not regular season titles so that is sort of a big downside for him grabbing the conference award. Voted before Big 12 tourney so runs there don't count either.
Guessing this year it might be Jim Littell of OSU if you look at who did what in the conference. They lost a first team player to transfer (and insult to injury, to another Big 12 team) and were picked pre-season by the coaches to finish in 8th place. They looked to be one of the bottom teams that the top teams could be 10-0 against, not a top tier that would go 10-0 against the bottom five. Pretty big jump over expectations.
Fennelly has had multiple years where he should have received coach of the year. When Pop was a senior was a prime example. You can give it to the Conf champion coach easily...but who does the best job coaching? That is rarely considered.