To stand any chance of finishing in the top-half of the table the visitors had to win but were comfortably seen off by a Kris Commons double and a goal from Mikael Lustig.
The limp display left Fenlon fuming and he threatened his underperforming players with being axed for next week's William Hill Scottish Cup semi-final against Falkirk at Hampden.
"I don't think there is too many who came off the park who can have a moan if they are not in the team next week," he said.
"It gives me a lot to think about because that performance is not good enough. We had three or four who had pass marks, the rest didn't do enough.
"So it is a big week for people in training now. If they want to get into the semi-final team they are going to work tremendously hard to do that because I didn't see that from some of them.
"We didn't show enough commitment or have the belief that we could give ourselves a chance to get into the top-six.
"There was maybe a bit of acceptance rather than a desire to give ourselves a fighting chance and that is more disappointing than anything."
- Sports & Recreation
- Kris Commons