Have a guild trade option to go with the AH. if your player doesn't get picked up in the guild trade after 12 hours it goes to the AH or you can skip guild trade and put player directly into the AH. A 190 star player picked up by a lower lol guild member would go to that players max star limit but retain the points already accumulated
Guild Trade
It would be easy to stack teams without the competition of the AH. Dummy guilds could be made that did nothing but trade their good players to teams; and the teams could rotate through the guild to keep doing it. There are many ways this could be used to rig the game for certain teams and guilds.