Bruce was criticised by his former Wigan chairman Dave Whelan earlier this week over his signings.
Richardson thinks every one of the players signed so far at Sunderland has been a "class act".
He told The Journal: "I cannot really comment on what signings the manager took to Wigan. I don't know enough about them.
"What I can say is the players who have been brought here have all been top-class, great players, so all I am bothered about is Sunderland
"I watch a lot of football around the world and I knew John Mensah, Lorik Cana, maybe I did not know that much about Paulo Da Silva, but he came here as an international captain.
"You must have something about you. They are all quality players and they have all contributed to the team.
"Some players come with big names and take time to adapt, they don't sometimes. Our players have adapted and credit to the gaffer for keeping them on the right road."