Never was that more apparent than on Sunday, when his 95-yard catch from Ben Roethlisberger, the longest pass reception in Steelers history, set the stage for Pittsburgh's 32-20 victory over Arizona, the Cardinals' fifth loss in a row.
"You know he can run by you," Steelers coach Mike Tomlin said, "but he still finds a way to do it."
Arizona coach Ken Whisenhunt had studied tape of Wallace outracing one defender after another.
"We knew that was coming," he said. "We did everything we could to work to prevent that."
To no avail.
"You put it out there for a guy like that and you start smiling," Roethlisberger said, "because you know he is not going to get caught."
Roethlisberger, 26 of 39 for 361 yards, also had TD passes of 12 yards to Heath Miller and 4 yards to Emmanuel Sanders in the first game between the teams since Pittsburgh's 27-23 thriller over the Cardinals in the 2009 Super Bowl.
Kevin Kolb threw a pair of touchdown passes for Arizona (1-5), his first in three games, but missed several open receivers and, with a blitzing LaMarr Woodley in his face, drew an intentional grounding call in the Cardinals' end zone for a safety.
Pittsburgh (5-2) won its third straight and improved to 2-2 on the road.
Shaun Suisham kicked field goals of 41, 42 and 39 yards for the Steelers.
The big play from Roethlisberger to Wallace, cheered on by a crowd that included a generous and boisterous bunch of Steelers fans, came in the second quarter after an Arizona drive stalled at the Steelers 39 and Dave Zastudil's 30-yard punt pinned Pittsburgh on its 9-yard line. A false start penalty pushed it back to the Steelers 5.
On the next play, Roethlisberger dropped back into the Pittsburgh end zone and lofted a pass down the sideline toward Wallace, who had beaten cornerback Richard Marshall.
Wallace caught the ball in stride, breaking free of a pair of would-be tacklers along the way, and raced to the end zone for the score that made it 14-0 with 8:09 left in the half.
He said he was not the No. 1 receiver on the play but was trying to clear things out for Miller underneath.
"Their guy jumped outside and let me get inside," he said. "The safety was in the middle of the field so I just threw my hand up."
And the ball landed perfectly in his fingertips.
"A play like that kind of deflates them I would hope. I hope it takes a lot of out them but they kept playing," Wallace said.
The previous longest pass play was 90 yards, first set by Terry Bradshaw to Mark Malone against Seattle in 1981, then matched by Bubby Brister to Dwight Stone against Denver in 1990 and Kordell Stewart to Bobby Shaw against Baltimore in 2001.
It was the second-longest play from scrimmage for the Pittsburgh franchise. Only Bobby Gage's 97-yard run against Chicago in 1949 was longer.
Down 17-7 at the half, the Cardinals cut the lead to 17-14 with 9:26 left in the third quarter when Kolb threw short over the middle to LaRod Stephens-Howling and the 5-foot-7 back outran defenders on a 73-yard touchdown play.
Pittsburgh scored the next 15 points.
"I still don't think we are there," Roethlisberger said. "I think we are getting closer. There are still some things we can do to get better but that is good. It is early in the year still and we need to make those improvements. We don't want to be just clicking at 100 percent now. We want to be winning games and moving forward."
The Steelers rolled for 445 yards in a successful warm-up to next Sunday's home showdown against New England.
The Cardinals find their season on the brink of disaster. Arizona plays four of its next five on the road, beginning next Sunday at Baltimore.
The Cardinals have lost 10 straight road games, their past win at St. Louis in the 2010 season opener.
Kolb, acquired from Philadelphia then signed to a five-year, $63 million contract -- with $21 million guaranteed -- still is struggling with the Arizona offense, although he insists things are getting better with each game.
Arizona was coming off a bye week and Kolb had talked about how good the practices had been.
"I feel from a personal standpoint, in and out of the huddle, the plays, it all came a lot smoother to me today," he said. "Obviously there were a couple of throws that I would like to have back. Those plays need to be made. That's me, too."
Against the Steelers, Kolb was 18 of 34 for 272 yards and two scores, with one interception.
The pick came after Arizona took the opening kickoff.
On first down from the Cardinals 27, Kolb threw to rookie tight end Rob Housler. The ball bounced off Housler's helmet into the arms of the Steelers' Ryan Clark, who returned the interception 10 yards to the Arizona 31.
Five plays later, Roethlisberger threw 12 yards to a wide open Miller for the touchdown.
After the stunning 95-yarder to Wallace, the Cardinals mounted their first scoring drive.
A pair of penalties against Ike Taylor, who played a physical defense -- usually against Larry Fitzgerald -- throughout the game, aided Arizona's 13-play, 80-yard drive that ended with Alfonso Smith's 1-yard run with 1:25 to play.
But aided by three penalties against the Arizona secondary -- two on Patrick Peterson -- the Steelers drove for a 41-yard field goal by Suisham as the half ended to boost Pittsburgh's lead to 17-7.
Arizona running back Beanie Wells rushed for 42 yards before leaving the game in the second quarter with a sprained right knee. Pittsburgh wide receiver Hines Ward was carted off in the second half with an ankle injury.
Miller caught four passes to move ahead of Franco Harris for sixth in Steelers career receptions with 308. ... Fitzgerald caught four passes for 78 yards. Arizona's struggles could endanger its streak of sellouts, which dates to the opening of University of Phoenix Stadium in 2006. Arizona's next home game is Nov. 6 against currently winless St. Louis. ... The Cardinals are 6-16 since Kurt Warner retired. ... Malone was a rookie quarterback filling in at receiver for Lynn Swann when he caught the 90-yarder from Bradshaw.