Right now, it looks like a new league starts with a randomized pool of players, then there is a draft based on random preferences for each team. The coaches are already assigned and the GM starts out with this setup.

Instead, I think the coaches should all be free agents and the GM should have 3 sims to sign coaches before the sim automatically signs coaches to your team. This allows a player the opportunity to find a coach that fits your preferred type of offense/defense.

Then, you can do the players three ways...
1) start out with all players as free agents, and let everyone fight it out in free agency from the initial player pool.
2) have a full fledged, 53 round serpentine draft.
3) have the GMs set up their preferences and run the preference draft in one sim.

All this gives a GM more control over how their team starts out. Start off with the coaching staff, then put a team together that works best with the coaching scheme and the GM's vision of the team and game. I think this would also give GMs more reason to play more than one season then leave, as they are immediately more immersed in the game and invested in their team.

You could also allow all teams to start out with the same basic coaching staff but allow GMs to pick their offensive and defensive play book/style/whatever you call it.