The Grecians held Brentford 1-1 in the first leg of their Johnstone's Paint Trophy clash, but bowed out 3-2 on aggregate thanks to goals from Sam Saunders and Gary Alexander before Daniel Nardiello hit a late consolation.
Tisdale said: "We lost it right from the start.
"We lost to a team, we were not a team, and I am not happy with the performance. I think Brentford thoroughly deserved their win.
"We didn't start the game well and I am embarrassed by the team's performance.
"I don't know why. Sometimes these things happen and I will look at it, but the chance has gone. We have lost our chance and Brentford deserve their win. We didn't compete, we didn't play well, we didn't attack the goal properly and we didn't defend our goal properly."
Source: PA
Source: PA