The Clarets cut the gap to the top six to three points after debutant Nathan Delfouneso's fifth-minute goal secured a vital win.
"The disappointing thing is we've been beaten by a really poor goal" said Pearson. "They'll probably think it's a good one. It's the first time that corner has worked - we've seen it a few times on the DVD and we know what it's about.
"That's a sucker punch. But we've haven't played well, that's the bottom line."
Hull found clear-cut openings hard to fashion and when they did arrive, profligacy cost them. But Pearson refused to rule out his players' promotion chances in the wake of a damaging loss.
The Tigers are now seven points off the play-off pace and Pearson added: "The players feel a bit frustrated they haven't been able to get into their stride.
"There's still 10 games left, 30 points to play for. People might write us off, but that might be good for us."