A bizarre own goal from Esteban Cambiasso was enough to settle Saturday's encounter at the King Power Stadium, as Leicester's winless league run stretched to five matches.
Manager Pearson felt his side put in a far improved performance from last weekend's 2-0 loss at Swansea City, but conceded Leicester must do better in the final third.
"I can't do much about it [the own goal]. It's unlucky," he said.
"I was pleased with the fact we were more solid and disciplined. The work ethic was there, we didn't create many opportunities but I thought we were pretty comfortable in the game.
"In the context of last week's [performance compared] to this week's there were positives.
"It doesn't help in the sense we have no points out of it but if you're looking from our baseline performance I wouldn't be too displeased with how the players have gone about trying to get the right result.
"Ultimately it's going to be about the quality at times that we've not really shown in the final third whether it be the final ball or the finish. In a game of few chances we probably had the best openings and didn't take them.
"We were in a game today to try and win it, it was an unfortunate series of events that allowed West Brom to win."
Pearson also explained that top scorer Leonardo Ulloa was left on the bench as the striker has a slight groin injury.
"He had a groin problem which we had scanned last Sunday," he added. "It was a case of not wanting to risk him from the start."
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