All coaches hire their 'buddies' aka coaches they have a relationship with and have worked with before, so I generally advise people against worrying about this too much. I would particularly advise against extrapolating what Frost did with his UCF staff towards other coaches hiring people they've worked with before. It's not necessarily predictive of success or failure.
Besides, if he hires people who helped him win 10+ games at Temple and 10+ games at Baylor, I would look at that as an objectively good decision.