I think the most you can say is the best at building a farm. =======
It's too early to suggest even that. The Padres, Diamondbacks, Braves, and Nationals all have great farms that have been built on good drafts and thoughtful trades. Luhnow has to get a bit of a track record -- beyond then handful of months -- before you can objectively say he is the best.
"I think the most you can say is the best at building a farm."
Not as long as Mike Arbuckle is alive and well.
"Who is he with now? I didn't realize he was an NL GM, last I heard he was fired from the Royals and I can't remember hearing about him taking an NL GM job since then."
His name is Mike Arbuckle and no, you didn't hear he was fired by the Royals because it didn't happen. He's still there doing his thing. But you are right he isn't the GM so I will change that to Dayton Moore. The man with enough sense to keep Arbuckle.