The Gulls lost 3-2 to Wycombe on Saturday and are one point above the relegation zone after five defeats in six games.
"I've got a good group of players and an honest group but I need more than honesty," he told BBC Radio Devon.
"It's no good being excellent Monday to Friday. We're judged on a Saturday and we weren't good enough.
"We can't keep conceding as we are - if players are putting it in the top corner from the edge of the box then fair enough but we gave away three poor goals."