I agree with a few theories on this. Brubaker has some dangling plot threads from his run on SECRET AVENGERS as well as STEVE ROGERS: SUPER SOLDIER, which tied into that in the end.
Considering "AVENGERS" in May 2012, I wouldn't be surprised if the "clog the panels with copies of a popular hero" formula was extended to Cap. Marvel's done it with Wolverine, Hulk, Thor, and Spider-Man all within the last couple of years. On the other hand, DC did the same with Green Lantern. In the 90's, it happened to Venom (sort of). It doesn't usually work long term and is often mocked long term, but to be fair, SPIDER-ISLAND's likely been the best of the lot - likely because it wasn't line wide (or spawned a family of titles like with Wolverine).
The somewhat annoying thing is that Captain America has been imitated many, many times. Red Skull used to literally house his mind in a clone of Cap. Protocide was a retcon super-soldier in the 90's and later on we got RED, WHITE AND BLACK that added more. The Power Broker formula was meant to create an enhanced version that brought us G.I. Max and U.S. Agent, among others like Battlestar and so on. For the record, the Power Broker formula was superior - those who got it got Class 10 strength (basically, the strength of Spider-Man), rather than "peak human" strength.
It could be that Bucky wasn't the only Winter Soldier, and perhaps Brubaker is dusting off some other seemingly dead WWII relics to use as Commie sleeper assassins. Who knows.
The closest thing to a Brubaker written event was CAPTAIN AMERICA REBORN, and while that was far from his best work, it's leagues above FEAR ITSELF and even SIEGE to a degree. But I think the common thread in all these disasters of narrative is editorial. Something happens or doesn't happen at the top which makes things go off the rails. Maybe the desire to sell books over telling a narrative hits critical mass.
