Like Pennant, Diao also signed with the Potters on transfer deadline day.
He told The Sentinel: "He's a typical winger in that he can beat people, is very good at one-on-ones and he puts great crosses in.
"He has a great right foot and can give us that width on the right side.
"I see him as a complementary player to Matthew Etherington, who has done very well for us.
"In the way we play, we defend a lot in the middle so we need these guys who are physically unbelievable and can run with the ball.
"Every time Matty has the ball, we know he's going to run with it for six or seven seconds and that gives us time to push on up the pitch."