As noted earlier, even the best GM's can make mistakes. Bing Devine had a stellar reputation, but he sure made some stinkeroo trades in the 70's, and you can't put all those on old Gussie.
Walt was an excellent GM, but he too had some stinkers - Young for Brantley comes quickly to mind.
For a guy for whom this is his first big league GM gig, I think Mo's done right well. Whether the Ryan deal is one of his stinkers or not is irrelevant - overall, he's done a good job.
"You have to be concerned about the future, but you also have to be more concerned about the present. If you have to give up two or three young kids - who may not be able to play for several years - to get help for your team now, you have to do it." - Bing Devine, 1999
"They call baseball a game because it's too screwed up to be a business." - Jim Bouton, 1971.
"Big deal. Anyone can win games when the other team doesn't score any runs." - Curt Flood to Bob Gibson, circa 1968