I don't have time to go too in-depth right now but I have a few basic comments.
1. Recruit better players. These players are not D-1 caliber: Davis, Rykowski, English, Jackson, Russo, and Dvorak. Their lack of Athleticism and Defense has to be killing you. I suggest having a few bright line rules in your head when recruiting. For example, I don't recruit any post player that will fail to reach at least 70 in ATH/REB/DEF for my M2M defense and that is an absolute minimum. For zone, BLK is also a core for post players. For perimeter players I also target a minimum of 70 DEF.
While 70 is too low for a good D-1 team, it should give you a starting point for weeding out unacceptable recruits. You should definitely try to get players who will end up above 75-80 in their cores, but there are occasionally useful players that don't quite reach that level in one category but make up for it in others. Kurtis Adkinson (
https://www.whatifsports.com/hd/PlayerProfile/Ratings.aspx?tid=11992&pid=3681185 ) is a PF on my Oklahoma team and has an ATH of 71. He finished 2nd team all-conference though because he is 95 at REB, 99 DEF, 90 LP, and 50 SPD. Someone with D-1 zone experience can get more specific with what they target for difference positions.
2. Run slowdown. Your starters are vastly superior to your bench so you should be trying to maximize the amount of time they are on the floor.
3. If you are running zone you don't need 12 players. You should focus on getting 10 good players and don't be afraid to take a walk on or two.