While speaking with ESPN's "Outside the Lines" on Thursday, Wenzlaff said McGwire's goal was to use steroids to get "bigger, faster, stronger" in order to improve his performance on the field. Wenzlaff told ESPN there's no doubt the array of drugs he provided McGwire helped him become a better home run hitter.
"Let me put it to you this way: If Paris Hilton was to take that array, she could run over Dick Butkus," Wenzlaff was quoted as saying by the network, which will air the interview at 9 a.m. ET Sunday on "Outside the Lines."
Wenzlaff was arrested on July 7, 1992, as part of Operation Equine, an investigation from '89-93 that led to more than 70 steroid-related convictions.
McGwire said in his interview with Costas that "in the winter '89 into '90, I was given a couple weeks worth, tried it, never thought anything of it, just moved on from it."
It was only later, following the injury-ravaged 1993-94 seasons, that McGwire says he once again began using PEDs to recover from injury. McGwire contends that his use from '94 on was a low-dose regimen designed solely to return him to health, not to augment his performance.
"I chuckled," Wenzlaff said when asked his reaction to McGwire's claim that he took steroids to heal from injury. "If excelling and kicking [butt] on the field is the end result, I guess that's a healthy, good feeling. But for health, there are other things you can take for health that are anabolic, but it wouldn't be that type of combination."
Wenzlaff also said he thinks the combination of drugs he provided McGwire would've helped his hand-eye coordination.
"When you implement into what you are doing -- for instance, hitting -- an individualized, specialized program with muscle growth and explosiveness ... while you're on your drugs, it will improve your hand-eye coordination," he said.
McGwire, the Cardinals' newly appointed hitting coach, then reintroduced himself to St. Louis fans during the club's Winter Warm-Up on Sunday and received a standing ovation.
Last week, now-retired FBI agent Greg Stejskal told ESPN.com that Operation Equine uncovered McGwire's use of performance-enhancing drugs in 1993 but never brought charges against the slugger because it was going after the dealers and not the individuals, like Major Leaguers, who benefited from it.
Alden Gonzalez is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.