The Rangers boss believes his side was guilty of missing several good goalscoring opportunities throughout the game and they paid the price in the 116th minute when John Baird scored a dramatic winner.
It was the first time the Light Blues had failed to score in a match this season but they certainly had the chances with a combination of poor finishing and good goalkeeping from Rovers’ keeper Lee Robinson making it a day to forget for the League One champions.
The manager said: “I’m extremely disappointed as you can imagine, as are the players. The game itself, we didn’t play well but I thought we had the better chances.
“When you don’t take them you obviously run the risk of losing a goal and that’s the way it worked out.
“We didn’t play well enough but we should still have scored given the number of chances we created.
“But there was a slackness about us on occasions defensively today and it came back to bite us.
“That was the first time we haven’t scored this season in a game and it’s our second defeat, albeit both of them have been in extra time. But it still hurts and I thought the manner in which we lost the goal was very, very poor as well.
“I’ve been here long enough as a player and a coach and a manager to know that there will be a lot of unhappy people, none more so than ourselves, the players and the staff.
“As down and as low as we are we can’t stay down there because we’ve got a massive game coming up next week.
“We’ll regroup and see how the injuries are in the next 24 hours and then we’ll start to prepare for a massive semi-final.”
McCoist confirmed that Lee Wallace, who was replaced after 65 minutes by Seb Faure in today's Final, has a thigh strain. He added: "He’s toiling but the boys were a bit patched up today to be fair to the two Nickys, big Daly and Ian Black.
"They didn’t train at all last week so to be fair to them they’ve put in a good effort today as in normal circumstances they probably wouldn't have been match fit.
“We have one or two wee kicks from today but I would say Wallace would be the biggest problem for next week. We’ll see how Black, Daly and the two Nickys are tomorrow as well.”
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