People bring up the AJ trade because they traded an above average player who had value in order to start a younger talented player at that position. At the time AJ had made 1 AS game, and has made 2 now in his 18 year career. While catcher is indeed a valuable position, talent at 3B is also fairly shallow. At the time the Twins traded AJ, he accumulated 5.6 WAR over his last 2 seasons. At the moment Trevor Plouffe has accumulated 5.7 WAR over the last 2 seasons. The biggest difference is AJ was 26 and Trevor will be 29 this offseason, other than that it's not a bad comparison at all. I think the problem with hanging on to him past this offseason is that is probably his peak trade value, at least IMO. After that he either becomes a 2 month rental at the deadline, which more than likely will bring back less or they lose him to free agency.