Now that the only coach worth bidding on market will be flooded, it's time to scrap the whole thing and start over.
Very simple. One coach at each level. No hiring. Just pick one.
Above average: All of your players will develop fully based on his ability, experience, playing time, etc., etc. 3m
Average: Most of your players will develop fully based on his ability, experience, playing time, etc., etc. 2m
Below average : Some of your players will develop fully based on his ability, experience, playing time, etc., etc. 1m
Everyone will get the exact level of coaching they expect. Coach hiring, which no one likes, will be simple. You'll spend 6m-18m on coaching. And, what I perceive the biggest "problem" with coaching, anonymity, will disappear. The recent addition of the HOF has driven home this point. No one can name their coaches from their winning seasons. But you remember the guy who had a career year.