Being World Class requires consistency; Marchisio is a solid player, but definitely not World Class. He is nowhere near as bad/horrible/invisible as some make him out to be, but he isn't some god on the pitch either like some members seem to think/believe.
As for the CL, the best team doesn't necessarily win. Milan in 03 & 07, Porto in 04, Liverpool in 05, Inter in 2011, and Chelsea in 2012. That's 6 out of the last 11 winners who had a solid team, but hardly one you'd expect to go on and lift the trophy.