We took their coach and director general, and they lost Cassano and Pazzini both half way through the next season (Cassano only played 7 games), so what happened afterwards has no relevance to the reliability of a squad he built. They lost key staff and personnel and replaced them with crap (Di Carlo/Cavasin; Macheda, Maccarone & Biabiany), that's nothing to do with Marotta.
It's certain that other teams underachieved to allow Sampdoria into the CL, but we don't know if the good work was a fluke and never will, so it's pointless saying it. A club like Sampdoria has obvious limitations.