On Monday night, he proved that theory wrong.
Tejada's two-run homer in the bottom of the ninth gave the Astros a 5-3 win over St. Louis, snapping a five game winning streak for the Cardinals.
"I think he's way better than the guy we thought we were getting," Astros manager Cecil Cooper said. "They said he'd lost a step. He hasn't lost a step."
Cooper and teammates have been impressed by the energy of Tejada since he joined the team. He hasn't appeared distracted despite the FBI investigating whether he lied about steroids to investigators for a House committee.
"Every time I stepped up to the plate it was so exciting," he said. "I just wanted to do something for these fans."
The Astros led 3-0 before the Cardinals' three-hit ninth inning. Ryan Ludwick's two-out, two RBI double off closer Jose Valverde (2-0), who blew the save, tied it at 3 in the top of the ninth. Cesar Izturis scored easily on the hit to right-center field. Astros catcher J.R. Towles was in position to tag Troy Glaus at home but couldn't hold onto the ball during a collision and Glaus scored the tying run.
A single by Aaron Miles and a walk by Izturis set up an RBI single by Glaus.
Yadier Molina grounded into a force out to end that inning.
Valverde, who led the majors last season with 47 saves for Arizona, was disappointed in his performance.
"I just threw some mistakes tonight," he said. "I was throwing too hard. But that's all right, I'll be back tomorrow and I'll forget this."
Back-to-back homers by Lance Berkman and Carlos Lee broke a scoreless tie in the seventh inning. Berkman's home run, which came off Cardinals starter Todd Wellemeyer, bounced off the wall in center field and put Houston ahead 1-0. Lee followed with his third home run of the year, a shot that bounced off the facade in left field.
The Astros got a solid performance from lefty Wandy Rodriguez, who pitched 7 1/3 scoreless innings with three hits, six strikeouts and no walks. He didn't receive a decision because of Valverde's blown save.
"I'm a little disappointed for Wandy's sake because he had a great outing," Cooper said. "It's probably the best I've seen him. He was attacking the hitters with his fastball."
Towles added a run with a solo homer to left field off Kelvin Jimenez in the eighth inning.
After Albert Pujols singled with two outs in the first, Rodriguez retired nine straight batters. Glaus doubled after that, but Ludwick struck out swinging to end the fourth inning. That out was the first of 11 straight outs for Houston and Rodriguez wouldn't allow another hit until he was chased by a single by Molina with one out in the eighth.
The Astros had managed only a pair of singles against Wellemeyer, a leadoff one by Michael Bourn and one to start the fifth inning by Tejada, before the pair of seventh-inning homers.
Wellemeyer allowed five hits with two runs, seven strikeouts and a walk. He struggled with a nosebleed for almost four innings Monday.
"It must be the hot weather or something," he said. "It started in the first inning and didn't stop until the fifth. When I came off the mound in the first, it started pouring. I don't know why."
Cardinals manager Tony La Russa was impressed with his performance. He has a 2.25 ERA in two starts.
"He's given us two outstanding starts," La Russa said.
Bourn, in his first year playing for his hometown Astros, upped his stolen base total for the season to six with a pair on Monday.
It was Houston's home opener after opening the season with a seven-game road trip. It was the first time since 2000 the Astros didn't open the season at home.
Astros third baseman Ty Wigginton will miss the St. Louis series with a small fracture in his left thumb. The team is trying to avoid placing him on the disabled list, but he will be re-evaluated on Thursday and such a move could be necessary. ... Astros second baseman Kaz Matsui, on the disabled list after surgery to repair an anal fissure, has been cleared to play and will begin a rehab assignment Tuesday with Double-A Corpus Christi. He could return to Houston's lineup as soon as Sunday. ... Cardinals left fielder Chris Duncan returned to the lineup after missing five games with a strained left hamstring. ... Cardinals right-hander Joel Pineiro, on the disabled list with a right shoulder strain, will have a rehab start for Triple-A Memphis on Tuesday.