Well boss McGhee said: "We can't deny they were a class above us. But we feel we have players who can genuinely aspire to that level. We can't say we can play better - because we can't."
McGhee, who admitted he got his first-leg tactics wrong, defended his unfamiliar 3-5-2 formation and his decision to leave out the in-form Jamie Murphy.
"We knew they would play 3-4-1-2 so rather than get overrun in the middle of the park, I thought we would match them," he said. "To a large extent that worked fine - the set-pieces stitched us up.
"I think we got our tactics in the early part of the game right. We didn't do the practical things well.
"We spoke about not conceding free-kicks and the way the referee would interpret things.
"I felt there was a free-kick on Paul Quinn before the free-kick was given against him, but the referee didn't see it. But Paul has been suckered.
"And when the ball was saved, I expected us to be faster to the rebound. The second one was one of these things."
And the Fir Park boss also defended his pre-match comments when he accused Nancy boss Pablo Correa of treating them with contempt and declaring Well would try to "kick them in the teeth".
"When I said that I was being euphemistic," he said. "I meant kicking them in the teeth in terms of trying to beat them.
"I made sure I shook his hand before the game so he understood before a ball was kicked that there was no problem."
Correa denied the comments had motivated his team before what he described as the "ideal match".
"We weren't present when the comments were made and we proved our abilities on the pitch," he said. "We didn't have any idea Motherwell felt that way but it was proven in the match that Nancy were the better team.
"We haven't had the chance to talk but I regret that Motherwell felt that way and I would like to rectify that."