I really dislike that you can sign a position coach and they get poached the very next season. That really doesn't happen in the NFL. They usually work a few seasons and then get signed when they are out of contract.
I have two suggestion -
1 - Allow a position coach to work a minimum time before poachable (is that a word??)...for example, maybe a on a 5 year contract, he has to work 3 seasons or be released before another player can go after him
2 - there should be compensation pick(s) given to the team if their staff is poached while under contract