"We didn't play well, simple as that," he told Sky Sports after watching the Saints go down 11-27 to the Cherry and Whites.
Jonny May's double had undone the home efforts, but equally frustrating was both the manner in which the scores had been conceded and how Saints had failed to finish off their own three good scoring chances.
"They didn't have to play much rugby against us," Mallinder added. "We were poor. We had try opportunities we didn't take and conceded poor scores.
"After their try at the start of the second half the confidence went from the team and we started making elementary mistakes. We didn't perform, simple as that. It's certainly something to address during the week and we need to find the magic ingredient.
"The silly penalties didn't help, but the game was decided on conceding soft tries. Sometimes you win by scoring points, but sometimes you need to defend well and we didn't do that.
"We've got to go to Worcester and get a win. We're still in touch but have made it tough for ourselves. We have some issues to address and we need all our team to play well.
"As players and coaches we've got to take that all on board and get better."