"Big-league pitching - legitimate, starting, big-league pitching - does not grow on trees," McCullers said Sunday while discussing a potential extension, according to Chandler Rome of the Houston Chronicle. "And I'm a legitimate big-league starter, and I've worked really hard to get to this point."
The right-hander said he "undoubtedly" wants to stay with Houston "well into the future" but added the team has not yet discussed an extension with his agent Scott Boras.
McCullers, 27, is eligible for free agency in 2022. Boras normally prefers his clients test the open market, but McCullers has given him specific instructions regarding Houston.
"I have told Scott if the Astros call, if they're interested in it, that it is something we want to pursue," he said.
McCullers was 3-3 with a 3.93 ERA and 3.70 FIP in 55 innings for Houston last season. He missed the 2019 campaign while recovering from Tommy John surgery.
The former first-round pick owns a 32-25 record with a 3.70 ERA and 1.26 WHIP in five seasons with the Astros, helping them win the World Series in 2017.