In the modern era of baseball, player movement is a given. Teams make trades and players become free agents; rarely does a player make it through his entire career with one franchise. But sometimes, teams make a deal where a current or future star is moved while still playing in his prime. That can be a trade that haunts a franchise, but sometimes it works out well for all involved, too. We looked at 20 current MLB players who made it to the big leagues with one team, then were traded away while still in their prime.