Dundee United head coach Craig Levein blasted his side's defending after the 1-0 reverse at Kilmarnock.
A Peter Leven goal on the hour settled the Rugby Park clash and Levein was less than impressed by some of his players.
He said: "We defended well in the first half, but as good as we were then, we were as bad in the second.
"It's down to individual errors. If it was the same individual every week it would be easy to sort out, but we have players playing well one week and then hopeless the next.
"We've had two clean sheets in 14, it's nonsense.
"I should be able to field two centre-halves who give me seven out of ten every week, not eight one week then four the next."