Yusmeiro Petit hardly inspires thoughts of the near-perfection demonstrated by San Francisco Giants teammate Madison Bumgarner in his one-hit shutout Tuesday.

The journeyman right-hander from Venezuela barely touches 90 mph with his fastball, and he hasn't won more than four games in any of his seven seasons in the majors.

But when Petit takes the mound against the Colorado Rockies on Thursday, replacing the struggling Tim Lincecum for at least one start, he will be carrying a streak that goes well beyond the 27 consecutive outs required for a perfecto. Furthermore, less than a year ago he took his own bid for immortality even further than Bumgarner's seven spotless innings.

Petit, 29, has retired the last 38 batters he has faced – over seven outings – just seven short of the record set by Mark Buehrle with the Chicago White Sox in 2009. Petit's streak, which he didn't know about until recently, is tied for the sixth longest ever.

It's an unlikely accomplishment for a pitcher with a career 4.84 ERA who spent the 2011 season with the Oaxaca Warriors of the Mexican league. For that matter, so was his near-perfecto against the Arizona Diamondbacks on Sept. 6, spoiled by Eric Chavez's two-out single in the ninth.

Both achievements speak to Petit's growth as a pitcher and his ability to adapt. Teammate Pablo Sandoval first faced Petit in 2009 and pointed out he's very different now.

"He didn't know how to pitch before,'' Sandoval said, "and I think what helped him get back here was pitching in the Mexican league, which has a lot of veterans. You need to know how to pitch in that league.''

And at the major league level, you need to establish your fastball. That's something Petit was reluctant to do early in his career, when he bounced around between the then-Florida Marlins, the Diamondbacks and the minors.

Starting in 36 of his 71 games from 2006-09, Petit compiled a 10-20 record with a 5.57 ERA. He spent 2010 in the minors and nearly all of 2012 as well, plus the 2011 season in Mexico. As a long reliever and spot starter for the Giants the last two years, Petit has gone 7-4 with a 3.58 ERA in 41 games, 13 of them starts.