Danny Rose stole a 2-1 victory for the Stags at the death and Bentley said: “The game today just sums our season up.
“We had two good opportunities when we should have scored, they whack the ball up and score.”
He was very impressed with matchwinner Rose.
Bentley said: “I have to say Rose is one of the most complete forwards in the division. He set the first goal up and scored the winner.
“You can see why Bury paid good money for him and he's scored 12 goals in 24 appearances now.
“His all-round play, his leap for a lad of his size, his link-up play, work rate, technical ability and tactical awareness are all good.”
Bentley has to take the positives, but believes his side is not getting the rub of the green with results.
“It's disappointing but I have got to be proud of them,” he said. “When I am critical I am right to be critical.
“I have to say I think Mansfield probably smashed and grabbed today, but I can't recall is having a smash and grab apart from Cambridge away when they battered us and we got a 0-0.
“But I can't keep coming in and saying lads remain positive, you've lost a game but it's a game you should never have lost.
“Let's get it right. Before a ball was kicked this season Mansfield were favourites to win the division. So, on that evidence, I think we are doing all right as everything is stacked against us compared to a club like Mansfield.
“We played with heart and desire today, created numerous chances and on another day we'd have won it.”