Preller hasn't done that badly in terms of prospects, though. His first offseason, he indeed gave up Trea Turner and Joe Ross. He also gave up Yasmani Grandal, although he wasn't a prospect anymore. But he also got Justin Upton and Craig Kimbrel relatively cheaply, as well as Wil Myers and Derek Norris, who have generally been solid (Norris' recent collapse notwithstanding). Then in his second year, he turned around and got a nice prospect haul for Kimbrel, and also got Pomeranz for Alonso and flipped him for a top prospect, moved Cashner for prospects, flipped Rodney, and managed to unload James Shields in the nick of time. Also got a comp pick for losing Justin Upton. If you account for Turner's crazy BABIP and Ross's low ceiling, and give him credit for adding Margot and Espinoza, Preller has probably been close to net neutral in terms of prospects. Still has Renfroe, Nix, Allen, and even Hedges too (who is no longer prospect eligible but is only 23 and has showed some promise in AAA). His main problem seems to be targeting the wrong MLB players and not getting enough present-day performance from them (i.e. Kemp).