The victory at Easter Road allowed Saints to leapfrog their hosts into fourth
spot in the SPL with a late consolation by Leigh Griffiths the only bright note.
Fenlon said: "It was bitterly disappointing to be honest. There was nothing in the game up until the first goal but, after that, we were all over the place and it wasn't good enough.
"I thought St Johnstone played really well but they also worked tremendously hard and we didn't have that tonight. I can't say that too many times about my team this year.
"But definitely tonight we lacked that little bit of urgency, hunger and desire. They looked like they wanted it a little bit more than us."