Cook saw his players go behind to goals from Joe Bryan and Curtis Nelson and, although Guy Branston scored an own goal, Plymouth deservedly held on to move four points clear of the drop zone.
"We just didn't turn up," Cook said. "The first 20 minutes looked like an end-of-season game. We have lost again, the pattern is there and the pattern doesn't change.
"We can't win every game and I don't have issues about getting beaten but in a game like tonight, which was our biggest of the season, when the players knew how important it was, we didn't turn up.
"Our consistency is our inconsistency and it doesn't go away. I am physically sick. We have rolled over to a team that started OK but didn't put us under a lot of pressure. You need a group of characters about the club that demand success and drive the team forward, but we don't have that at the moment.
"People will look at the table and say we still have a chance, but if we start games like that we have no chance."