The Grecians slipped to eighth place in the League Two standings after their fourth consecutive defeat and Bradford, who leapfrogged them, still have one game in hand.
But Tisdale is remaining positive, despite seeing his side outclassed by the Millers at the New York Stadium, and believes City did well to recover after trailing 3-0 after just half-an-hour.
"The first goal was an error in midfield and after that we got rolled over," he said.
"We could have lost by five or six, but we didn't. We certainly played with some strength of mind and I have to say I think they did okay. It could be a turning point.
"We might be down, but we are not down and out. Maybe the opportunity has gone, but we will just have to see what happens."