All that broken ground makes it so odd that for much of the two decades Frost was gone, a program that prides itself on laying the foundation for modern college football strength training had lost its identity — and lost a hefty number of the games it used to win as a result. (si.com)
The method was then further popularized in the 1970's by legendary football strength coach Bill Starr, who used it to train all his athletes. (whatreallybuildsmuscle.com)
Here is a good article on Football Weight Training that includes authors Jim Wendler (asst. football strength coach at UK) and Sal Alosi (Head Strength Coach of Atlanta Falcons) all mentioning squatting in their most important exercise index for football. (personalfitnessadvantage.com)