Birmingham boss Lee Clark felt his team's season was captured in 90 rain-swept minutes at Pride Park as Derby edged a five-goal thriller to clinch a third straight home win.
A double from Conor Sammon and a late strike by substitute Nathan Tyson edged out Birmingham, who twice came back through a Marlon King penalty and a Peter Lovenkrands header.
"I thought our second-half performance warranted something but our first-half performance didn't," Clark said. "It's a good summary of our season really, it's a Jekyll and Hyde performance in one game.
"It's been like that game to game for us. We've played well in one game and the next it doesn't look the same team but we had it in one game tonight.
"The first half wasn't our true identity but the second half was. I said to the players at the end that if we play like that from the first whistle and don't allow the opposition to get momentum and get on the front foot, we will get a result."
However, Clark believed his team was hard done by with crucial decisions going against them, and he added: "I don't want to make excuses but facts are facts.
"The first goal was offside, that's a fact and the second goal, Marlon King has been fouled on the edge of the box. I've seen the incidents again and that's what happened."
Derby manager Nigel Clough hailed the victory as a reward for the honesty of his team, and he said: "It's about character, determination and it's also honesty as much as anything from the players.
"Their honesty is incredible. They never give up, they keep going and keep trying to do the right things.
"I thought the manner of the third goal was as good as anything. It was a brilliant goal, it came from the right, was dotted across and ended with a sidefoot and a tap-in inside the six-yard box, not many goals finish like that."