Report: Astros promote top prospect Francis Martes

The Houston Astros already own the best record in baseball, yet they still felt it was necessary to improve their club, promoting top prospect Francis Martes to the big-league squad, a source confirmed Thursday to MLB.com's Brian McTaggart.

Martes, the No. 15 prospect in all of baseball according to MLB Pipeline, was scratched from his start at Triple-A Fresno on Wednesday and is likely to fill a long-relief role in the Astros' bullpen, according to McTaggart.

Houston's bullpen has already logged over 200 innings, good for sixth in the American League. The team was forced to use reliever Dayan Diaz as its starter Wednesday before the bullpen took over and pitched 5 1/3 innings.

The 21-year-old Martes, a native of the Dominican Republic, has had a tough time this season at Triple-A. He's posted a 5.29 ERA across eight starts, including a 2.10 WHIP, but the hard-throwing right-hander features a fastball that can reach 98 mph and a good curveball as a secondary pitch.

Martes was acquired in a trade from the Miami Marlins in 2014.