I just see it differently. Jalen was, in his mind at least, the PG and leader of this team. He was recruited as a PG and played 100% PG at Brewster. That's the role he needed. Gilbert is a PG, but as you said he needed time behind someone else, that someone was Adams. Purvis is a SG, so his role was made unfamiliar as well. Facey has had underutilized talent for four years. He put on muscle in the offseason and should have been given a greater opportunity. It's Ollie's job to find out what has has before the games start for real. I think he probably let his own biases towards small lineups impact his decisions and it cost the team. The team was ranked #18, and this was no "transitional" year. Kentucky has those kinds of years every year. It's on the coach to figure it out and quickly, before you lose games to lousy teams, at home. To start the season everyone but Gilbert and Brimah were playing out of position, and Gilbert should have seen more bench time and Facey more floor time. It showed and we looked awful.
I'm no "fire Ollie" guy...hell no. But I suspect even he would tell you he did not do a good job in getting the team ready for the season or in utilizing what he had.