Hindsight analysis, they were on paper good enough to go for it. And from a business point of view, there are a lot of new fans that were deeply disappointed by the latter half of the 2012 season, when we basically tanked the rest of the year playing prospects. So they needed to make a splash or risk losing their new fan base. Previous poster was bang on, the idea was right but the execution and injury luck wasn't. In particular, after we did the Marlins trade, AA seemed to quickly dump several useful players that didn't fit his plan.
Sometimes risks have to be taken, playing it safe ( as JPR often did ) runs the risk of never winning either. Yankees, Angels, Dodgers, Rangers, Red Sox, Mariners ( re 2014 ) don't seem to mind taking big risks, and some of them do well and some don't.