Wilfried Bony scored both goals as Swansea ended a run of five Premier League matches without a win, but Leicester have now lost four of their five away fixtures since winning promotion to the top flight.
The visitors failed to register a single shot - on target or otherwise - during the first half at the Liberty Stadium, and Pearson says his players were not up to standard.
"We didn't manage the ball well enough, didn't give ourselves the best chance to win the game," he told Sky Sports. "We weren't positive and made too many unforced errors.
"We had some pace out there today, but unless you utilise your own possession, it makes it very difficult to maximise those players' strengths.
"We huffed and puffed but without the quality we've shown in other games.
"The way we've played so far this season, I know we're better than what we've shown today."
Pearson asked for the goals to be measured prior to kick-off, but was quick to explain the move during a post-match interview, revealing the controversy surrounding Garry Monk's comments about Victor Moses' alleged dive in Swansea's 2-1 defeat at Stoke City last weekend had been a factor.
"The goalkeepers felt they looked a bit big," he said. "I think Garry's had enough controversy in the last seven days, so it was prudent to check it out."
‘After Manchester City’s recent form, maybe they’re the underdogs against Manchester United!’ Former Red Devils defender on this weekend’s derby
‘Arteta, Alonso, Emery, me… none of us were physical players – we needed the understanding of the game. That probably helped us move into management’: Premier League boss reveals reasons for natural career progression
