After the Hornets had taken a two-goal lead, David Nugent pulled one back 19 minutes from time for the Foxes who had Zac Whitbread sent off on 83.
The visitors had a handful of penalty appeals turned down and Pearson said: "I have seen them again and whilst I have seen them given, I do not want to use them to mask the fact that we have not played as well as we could have played.
"That is two games running which is something we need to rectify relatively quickly.
"But what I would say is, as a group of players, so far this season they have been excellent.
"On the face of it, yes it has been a tough couple of games where we have not performed well as a team.
"But the reason for this is because we have too many players who are not quite hitting the very high standards of performance that they hit earlier."