Esteban Cambiasso's own-goal two minutes into the second half proved decisive at the King Power Stadium as Leicester struggled to convert pressure into clear-cut opportunities.
The defeat means Pearson's team are without a win in their last five fixtures - a run that included games against Swansea, Newcastle, Crystal Palace and Burnley.
"If you're looking at the baseline performance, I wouldn't be too displeased with how the players have gone about trying to get the right result," Pearson said.
"Ultimately though it's going to be about quality at times and we've not really shown enough in the final third whether it be the final ball or the finish.
"In a game of very few chances we probably had the better openings but we haven't been able to take them."
It was a scrappy goal that won the contest as Leicester captain Wes Morgan headed Saido Berahino's cross into Cambiasso and the ball deflected off the midfielder's body into the net.
Leicester could have snatched a point had Jamie Vardy or Andy King taken good chances in the second half but Ben Foster was largely untroubled in the West Brom goal.
"You could argue we were slightly unlucky today," Pearson said.
"On the back of our results we needed a more solid performance.
"I thought we had that, we didn't quite create enough clear-cut opportunities but we were playing against a side who do defend deep and are very disciplined in the way they defend.
"I could argue we were slightly unfortunate today but that's sometimes how it is."
The result means Leicester have nine points from their opening 10 games and the Foxes could slip into the relegation spots if Sunderland beat Crystal Palace on Monday.
Despite the club's inconsistent start to the campaign, Pearson is adamant his players do have what it takes to survive in the top flight.
"We do have a group of players who are capable at this level," Pearson said.
"What we haven't found is a way of consistently picking points up.
"I've got a very strong belief in the players we have but ultimately it's about finding a consistent level of performance that allows you to be in a game to win it.
"We were in a game today - we weren't last week against Swansea - and it was just an unfortunate series of events that allowed West Brom to win."
The Baggies' victory means they have now lost just once in their last six league games and Alan Irvine was thrilled with the victory, despite his side's scrappy winner
"I'm absolutely delighted with the result and I'm quite happy to take goals like that," Irvine said.
"It was fortunate the way the goal went in but it was a good move to get there.
"When you consider Manchester United, Arsenal, Everton and Burnley have all been here and none of them have won, I'm delighted.
"It was always going to be a really tough place to get a victory and while that wasn't the way I anticipated getting the victory, it was certainly welcome."
Leicester defender Marcin Wasilewski could face punishment after the defender appeared to deliberately elbow Saido Berahino.
Referee Stuart Attwell did not see the incident and Irvine admits he was also unaware anything untoward had taken place
"I haven't seen the replay but somebody else will deal with that (if it was deliberate)," Irvine said
"I didn't think any of it at the time so I certainly wouldn't have expected Stuart Attwell to see it either."
Source : PA
Source: PA