Andy Keogh's strike gave United a 1-0 half time lead, but Fowler soon took centre stage - netting a hat-trick within 16 minutes.
"Robbie has been a little bit disappointed and I can understand that, if I was in his position I would feel exactly the same,” said Pearce.
"There are various reasons why he hasn’t been playing. He was injured for a while, then you have to look at the form of Andy (Cole) and Darius (Vassell), plus the emergence of Bradley and, to some extent, Antoine (Sibierski).
"It has been difficult for him to break through but I have told him to keep his head down, work hard in training and take his chance. He can’t do much more than scoring three."