PSV dominated the match and managed 28 shots on goal, nine of which were on target, but could only muster a 1-1 draw.
The visitors had just one effort on target and struggled to keep hold of the ball and Cocu bemoaned his side's "clumsy" defending as they were held to a third successive draw in all competitions.
"We have now had an opponent who once has shot next and once on target, but they actually get the goals presented by us. That clumsy defense should not happen to us, that we may blame ourselves," said Cocu, as reported by the Netherlands edition of Goal.
PSV are currently fourth in the Eredivisie table and six points behind leaders Feyenoord, who could move further ahead as they travel to Nijmegen on Sunday.