Would MLB allow this?

So I’m sitting in my derivatives class and we’re studying credit swaps and I was also thinking about the recent injury problems the braves had undergone. The two topics merged in my mind and I started to wonder if you could trade a player and only receive in return something if some other event were to occur (for instance your closer going on the DL).

The example I came up with in my mind was the following: The Braves trade Tyler Yates to the Pirates. In return they receive nothing immediately. What they do receive is that in the event that Soriano is evaluated by an independent physician (agreed to by both teams) and the physician agrees he should be out for say 2 months, the Braves receive the rights to one player out of some pool of relievers (likely including tyler yates himself). This would be win-win. The Pirates get Yates, possibly for nothing, if Soriano stays relatively healthy. Even if Soriano goes down halfway through the season, they got Yates for free for a while. The Braves get to trade a reliever that was out of options and while they may not receive anything, they have the comfort of knowing that if Soriano went down they wouldn’t have to go around trying to desperately make a trade for bullpen depth. If Atlanta’s bullpen is fully healthy, Yates doesn’t have all that much value, however, in the event of injuries his value increases dramatically. The Pirates get a power arm for potentially nothing, and since they wouldn’t send him to the minors, the options concern isn’t the same for them.

Don’t know that MLB would ever allow it or that GMs would be advernturous enough to try it, but some food for thought.