There has been a rash of Tommy John injuries to starting pitchers. The Braves have two of their starters go down with season ending injuries. Tigers SS Jose Ingelias fractured bones in both his legs (which seems unbelievable), so he is out for the entire season as well.
Those bad breaks are opportunities for other players and other teams.
The Braves had to pop for free agent Ervin Santana because the team believes it can still win the NL East. The Tigers losing their starting shortstop is a major set back for the defending AL Central champions.
You don't have to wait to the July deadline to trade players.
The Cubs could sell "high" right now to teams that are reeling from injuries.
Even though their starting pitchers have been poor in the spring, the Cubs have several trade candidates: Samardzija, Hammel, E. Jackson, and even major league ready guys like Rusin, Grimm or Hendricks.
If the Tigers need a shortstop, Barney could be a caretaker. That would open up second for Bonifacio, the club's true lead off hitter until Baez is ready to be promoted next season. Or, in even a bolder move, Castro could be shopped for pitching prospects, clearing a path for Baez at his natural position.
This trade window will close sooner than you think. General managers are honing their rosters right now, seeing if they have minor league assets that can tide them over until the other teams make their final cuts.