"We conceded three terrible goals. There was nothing in the game in the first 20 minutes," said the 47-year-old.
"We're supposed to be a passing team. We just kept giving the ball away. Too many players didn't turn up.
"It's never nice to get beaten. We've got to roll our sleeves up now and go to Blackpool on Tuesday and get a result. Sometimes you learn more when you lose than when you win."
The defeat was Saunders's first since taking the manager's post at the Keepmoat last month.