Pearson said: "We got off to a good start and didn't back it up. I had to change the formation because of our inability to get back into a shape quick enough.
"We conceded two poor goals from our own perspective, but they would probably argue they were two good finishes.
"We should have managed the ball better, but we gave them something to build on, hang on to. Although we enjoyed possession, we didn't really look as dangerous as we should have done."
But Pearson insisted complacency was not an issue, adding: "No complacency. It's a word people overuse. No complacency. We had too many players having off days, if you like. We had a number of players who really struggled to reproduce levels of performance we expect."