It has been a tough season for United and Olsen was shattered for his men after the final whistle.
"I'm just gutted for the guys because they put so much effort into it and they want it so bad," said Olsen. "At the end of the day, whether it's a defensive lapse or - let's face it, we've got some chances to kill that game off.
"So it's not just a defensive display, it's both side of the play, making sure we're finishing the game off and making the plays that matter down the stretch."
Olsen admitted his players had improved markedly since he took over from Curt Onalfo but admitted they needed more efficiency in front of goal.
"We've got talent, we've got guys that we believe in," added Olsen. "I really like this team, I like the way they've responded. But again, it's not always enough to play hard. We've got to be smart and we've got to be clinical and we've got to get cutthroat when we've got the chances to do so."