Jonas Olsson put Albion in control after just five minutes with a close-range header before Graham Dorrans doubled their advantage in the 18th minute from the penalty spot. Luke Moore scored at the start of the second half before Gianni Zuiverloon and Simon Cox gave the final score a resounding look.
It was only Albion's second win in seven games and their first goals in three and Di Matteo said: "It is amazing we get all this criticism for not scoring in two games. We are still up there with the top scorers."
He added: "It is a very tough division and it seems to me that people expect us to be 10 points ahead of everyone else. But I cannot see any team running away.
"The criticism did upset me as we have a young team. I know at the end of the day it is all about results and we want to get results but people also forget we have very important members of our team who are missing."