James Dunne gave Smith's men the dream start after just nine minutes with the game's opening goal but two goals in 14 second-half minutes meant the Latics left with the points.
And Smith, whose team have now lost eight of their last 10 games, was fuming with their second-half display.
"On the behalf of everyone in that changing room I have to apologise to the fans for the display and the result," he said.
"It is the most disappointed and dejected that I've felt since I've been here and it came out of the blue.
"I thought the first half was probably everything we could have wanted other than to extend our lead because we had opportunities to do that.
"The second half was everything that we really don't want to be about, which was second best and eventually point-less.
"The same guys came out for the second period that performed as decently as they did in the first and they produced a 180-degree shift from the first half.
"Our efforts at goal in the second half were negligible - I don't remember us working their goalkeeper to any real extent - yet in the first half we were the only side that looked like scoring."