There has always been buzz that Pickens and Gundy don't get along, but that may have quited down last year:
https://www.tulsaworld.com/sportsextra/osusportsextra/osu-football-oklahoma-state-assistants-receive-cumulative-pay-bump-of/article_a56a8b28-e5f0-5dd5-8408-f5be3fcbb9be.html
Gundy was...