Mulder, 36, retired in 2009 after two surgeries on his left shoulder had reduced his effectiveness and sapped his hopes of pitching at an elite level again. He's been working as an analyst at ESPN since 2011, and had come to grips with the notion that his big-league days were at an end.
But things changed in October when Mulder watched Los Angeles Dodgers reliever Paco Rodriguez on TV and found something in Rodriguez's delivery that he could emulate. Mulder spent the month of November working himself into shape at a Phoenix-area facility run by former big-league catcher Chad Moeller, and recently threw off the mound for three unspecified teams near his home in Scottsdale.
He said scouts clocked his fastball at 89-90 mph. Now he's hoping to audition for more clubs and land an invitation to a spring training camp.
"I can't even begin to tell you how excited I am," Mulder said by phone Tuesday. "To be honest with you, I never anticipated this five or six weeks ago. It was just a flat-out fluke that came from me trying to imitate Paco Rodriguez in my living room."
Mulder, a former Michigan State star, began his professional career with Oakland in 1998 as the No. 2 overall choice in the draft -- one pick after the Philadelphia Phillies selected outfielder Pat Burrell with the top choice. Mulder was 23 years old in 2001 when he went 21-8 with a 3.45 ERA to finish second to Roger Clemens in the American League Cy Young Award balloting.
The Athletics sent Mulder to St. Louis in December 2004 in a four-player trade that brought Dan Haren to Oakland, and Mulder went 16-8 with a 3.64 ERA in 2005. But Mulder said his delivery and arm "never worked right'' after he underwent shoulder surgeries in 2006 and 2007.
A fluke viewing of Rodriguez on TV apparently changed that. Mulder had always separated his hands at his delivery at his midsection, but tried raising them near his head similar to the way Rodriguez does. He became convinced he was onto something after playing catch with former Cardinals teammate Kyle Lohse on Oct. 27, when they were hanging out at a birthday party for their daughters. The two pitchers threw from a distance of 150-200 feet, and Mulder was encouraged when Lohse told him he looked like his former self.
"The best way to describe it is, the ball is coming out of my hand better now than at any point when I was in St. Louis," Mulder said. "I wouldn't be trying this is if I didn't think the stuff I was throwing was good enough [to pitch in the big leagues]."
Mulder, who is under contract for two more years with ESPN, plans to put his TV future on temporary hold while he pursues his goal of pitching in the majors again. He expects to audition for several more teams before the end of December, and will see where his comeback takes him.
"So far everything has been awesome," Mulder said. "Why not give it a shot?"