He hired Nesbitt, who was fired after the first game - the Texas State debacle. He appointed Bush to be OC, who was abysmal, but apparently able to work with Levine, and Coogs went 5-7. Then, Levine brought in Meachum to take over play-calling and we promptly looked competent on the offensive side of the ball again. Coogs went 8-5. Meachum left for TCU, and here is the crux of the issue... After Bush had been ineffective as a play-caller two seasons prior, Levine appointed him OC again instead of finding another competent play-caller. This horrible decision resulted in the TDECU opening loss against UTSA. Despite finishing with a winning record, most agree that the offensive scheme was not the reason. It was the improvisation ability of Greg Ward.
And so, that is why people say Levine was stuck on Bush. He appointed him OC, not once (which could have been forgiven as Bush was a stop-gap in 2012), but twice with similar results both times.