I think this is the dictionary definition of collusion, and should not be allowed. If the guy was in reasonable contention would he make this trade, of course not. Honestly, if this isn't collusion I am not really sure what is.
I mean, imagine a situation in a h2h matchup where it was really close but the guy had a few saves on you, and you needed to get that back. So you agree with your buddy who is in a different matchup and doesn't need the saves to trade erik bedard for putz, and roy halladay for krod for the week, and then to trade them back afterwords. How can this _not_ be collusion?!?
There was an article on espn's "commish's court" about this type of player rental thing, and i agree with it being bogus. If your allowed to rent players back and forth two rosters essentially become one. Here it is http://sports.espn.go.com/fantasy/baseb ... commish728
Work out the full _real_ trade and go from there. If i was commish and this happened in my league I would veto the crap out of this, and give you a stern talking to about collusion and fair play.
I don't mean to be so harsh, but so many people in this section talk about only veto'ing trades because of collusion, and here it is smacking them in the face, yet there are so few calls for a veto.
Check out my blog at http://www.rotopulse.com for fantasy baseball analysis, injury reports, commissioner info and more.