WASHINGTON -- As D.C. United’s promising season came to a screeching halt at RFK Stadium, Ben Olsen could only offer an explanation as harsh as this nightmarish match felt: the loss of a competitive edge.


Sure, United had trouble with the Montreal Impact’s counterattacking posture in a 4-2 Eastern Conference Knockout Round defeat on Thursday night. And yes, breaking them down became even tougher after Laurent Ciman’s very early goal.


But after United’s first Knockout Round loss in its second such appearance, D.C.’s boss insisted defeat was simpler than shape and tactics.


“I don’t know if we’re reading our own press a little bit and thinking it was going to be easy and we were going to walk to the championship,” Olsen said in his post-match press conference. “But that’s not how it goes. There’s that edge there of [having] confidence. You need the edge and you need confidence, and if one starts to fade a little bit with each guy in this league, that’s enough to get punished for it.”


United had lost just twice in its last 14 league matches, and one of those was last Sunday’s regular season finale against Orlando City SC, in which Olsen played mostly reserves.


But D.C. went behind after only four minutes, and might’ve even been lucky not to trail sooner when Ignacio Piatti failed to punish D.C. for a giveaway only seconds into the encounter.


After Laurent Ciman’s opener -- the first scored by the defenseman since July of the 2015 regular season -- United could’ve still entered halftime optimistic had Matteo Mancosu not struck for the first of his brace three minutes before the break.


Mancosu pulled away from defender Bobby Boswell to tap in a simple finish of Piatti’s inch-perfect cross.


“I think if we would’ve gone in maybe 1-0 going into half, we would’ve been OK,” defender Steve Birnbaum said. “You know, we’ve been pretty good at not giving up soft goals like that throughout the year. I don’t think we did a good job in the back this game. All over, I didn’t think the energy was there.”