For the record - commissioners shouldn't push trades through during the regular season in order to circumvent Yahoo rules like DL limitations. I feel like silvergums asks us to do this 5 times a year so that he doesn't have to drop a player and we normally accommodate him, for some retarded reason.
No more!
If you can't just do the MLB part on Yahoo then the trade is rotten. The exception is if you are trading an MLB player for purely MiLB assets, then maybe a commissioner will add him to the other team so the owner doesn't have to waiver claim the player. That's it though.