Martin has proven in the past 2 years he can handle mountainous terrain (back again) like in the beginning of his pro-years. He wouldn't be able to do so in the highest mountains and he wouldn't be able to do so against climbers going for it.
However since the "climbers" in the chasing group didn't went full blow (but accepted the pace from the not-so-great Europcar guys) he could.
Furthermore, he had said at the end of the Saturday stage, he had a great feeling in his legs (which is probably why he put on his TT-suit in the morning of the Sunday stage to go into a long break and have a whack at it).
It was a great feat from a great rider, i'd drop it with that (unless future scientific evidence proves otherwise)
Something that has been for me (a bit too much) under-the-radar, is the other names that took some time back... people like Rolland, Feillu and Machado. Personally I think that Rolland and Feillu won't be that much with it (logic would dictate Rolland to start feeling the Giro in his legs in the later stages and Feillu hasn't shown much consistency in the last years).
However Machado has been riding a nice season (Criterium international, Giro Trentino, Tour of Slovenia), of course we don't know how he'll do in a 3-week stage, but with this move, he pretty much went from "protected rider/lieutenant for Konig" to NetApp main GC-guy. (Konig was a bit underwhelming this year anyway)
He just might be in with a shot to hold on to a top 10 placing.