The Manchester United striker was distinctly unimpressive last night as Fabio Capello's side laboured to a goalless World Cup Group C draw with Algeria in Cape Town.
Rooney did little to help his situation with a vitriolic rant at television cameras about the fans booing the team at full-time.
Barry, however, believes Rooney's role of talisman should not be questioned.
"We know we need Wayne," he said. "Wayne, at any time, can produce something magic."
Team-mate Jermain Defoe, a late substitute up front, concurred with the midfielder.
"As a forward, when you don't score for a few games you get frustrated and maybe you slash at things," he admitted. "But Wazza is a great player.
"He might nick a hat-trick in the next game, you never know. The good thing about Wazza is he always works hard, always tries and he wants to play well every game. He's got that spirit."
Barry played his first match of the tournament having missed the 1-1 draw with the United States while recovering from injury. Like his team-mates he was guilty of a poor individual and collective performance and was reflective after the match.
"It is disappointing," he conceded.
"Obviously, it was a big game for us today and we wanted to take three points. Our performance was probably a little bit flat, not attacking enough, but we're still in it.
"There were not really too many clear-cut chances. For England, that's the least we expect. We make the chances, like we did against the US. We didn't win the match, but we came out knowing we probably should have.
"We have to be confident. We spoke about it in the dressing room. We're going to stick together in the next few days.
"Everyone knows we'll do enough to get through.
"We play a very good team, so we have to put things right."
Barry and Defoe both revealed Capello's attempts to rally the troops after two poor performances left them needing to beat Slovenia on Wednesday to ensure they do not go home.
"He (Capello) is disappointed, but he knows everybody needs to stay calm in a situation like that," Barry added.
"We'll look at the video, and see what we didn't do right today. And hopefully put it right on Wednesday."
Defoe claims the squad remain confident: "The boss did say after the game 'just keep going'.
"He got our heads up, basically.
"He keeps telling us we're a great team and we'll win the next game."