George Boyd's well-taken goal barely 30 seconds after the half-time interval provided a rare moment of quality in a scrappy encounter.
Robins believed his side had turned a corner when they beat West Yorkshire rivals Leeds before the international break, but their sixth home defeat of the campaign leaves them just points above the relegation zone.
"We weren't good enough," Robins said. "I don't think it was a great game by any stretch of the imagination.
"We restricted them to very little, but it's a difficult formation to play against, how they play it and with the quality of players they've got, they're obviously up there for a reason."
Robins also complained that Town striker James Vaughan had been fouled in the build-up to Boyd's winner, but he was reluctant to blame that for the defeat.
"There was a real push in his back, but we can't blame incidents like that, we've got to come out and be better than this," he added.
"We go to Bolton on Tuesday and have seven games left. It's an interesting end to the season."