There is the same reason why Penn State doesn't field a good basketball team. Why Illinois, Purdue and Indiana don't field good football teams. Why Kansas fields an amazing basketball program but a broken football program.
The few programs that seem to excel in both programs are: Michigan State, Michigan, Ohio State, Wisconsin, Oklahoma, Florida, I'm sure a few others, but they are few and far between. Can it be done? Of course. But it basically takes landing on the right coach who will stay around for a while (I'm talking like 10 years+) to build something sustainable.
The alternative to landing on the right coach with a long tenure is basically shady recruiting. There is no evidence that Baylor has shady recruiting, but I'll go to my grave believing that they do. The rate of improvement across all programs is unheard of for a small town in the middle of Texas at a Christian school. Football, Men's and Women's Basketball all made quantum leaps and until the latest issues with the football program, appeared to be on track to sustain it.
Long post to say - stick with Miles.