No, I don't believe that a sole manager can suddenly render a ten-point title-winning side into trash. He should, however, be fixing it. But the players themselves should know better, absolutely. They are capable players who are not playing at their best at all. Also, Vidic is sadly not the player he once was. Guy can't be up there for headers (and he misses them, too - 10 corners, 0 goals from them) because he's too slow to get back to take care of any counter attack.