I'm not defending the play of the defense but he "core" of the defense in 2024 was Kizer, Watts, Cross, and Mills. Between the 4 of them, there is a combined 22 years of college football. That is not easily replaced. While this team may be more talented than last year, it is not as experienced as the '24 team.
It was clear to me being at the game and seeing things you don't see on tv that the defense looked lost and unorganized in the 1st half. Yes that is on the coaches but they simply don't have those 4 guys around who by instinct knew how to set up the defense and react to what is happening on the field that is not easily replaced.