Oswalt, 35, has the numbers to prove his love of the mountains. He's 4-0 with a 2.25 ERA in five career starts at Coors Field. In total, the 12-year veteran is 163-96 with a 3.28 ERA.
The Rockies have long coveted Oswalt and last year attempted to sign him before the Rangers reached a one-year, $5 million deal with him after the season began. Oswalt went 4-3 with a 5.80 ERA in 17 games, including nine starts. It was Oswalt's first extended bullpen duty.
The Rockies are looking at Oswalt as a starter. He'll likely join Double-A Tulsa once he is deemed ready. But Oswalt has been throwing extended sessions and facing hitters at home in Mississippi and could be at game speed quickly.
"We've had interest in Roy for some time," said Bill Geivett, the Rockies' senior vice president of Major League operations. "He's been a very good starter, and that's how we're looking at him. He's been successful at Coors Field, but he's also been successful everywhere."
The bulk of Oswalt's career was spent with the Astros, for whom he went 143-82 from 2001 until he was traded to the Phillies in 2010. Oswalt finished that season in Philadelphia 7-1 with a 1.74 ERA in 13 games, 12 starts. The following year he was 9-10 with a 3.69 ERA for the Phillies.
Thomas Harding is a reporter for MLB.com. Read his blog, Hardball in the Rockies, and follow him on Twitter @harding_at_mlb. This story was not subject to the approval of Major League Baseball or its clubs.