The Astros are 42-18, lead the American League West by 12 games and have four more wins than any other team in Major League Baseball.
On Thursday, they made a move to get even better.
Houston called up top prospect Francis Martes from Triple-A Fresno. The 21-year-old right-hander needed to be added to the 40-man roster before suiting up for the parent club.
According to MLB.com, baseball's No. 15 overall prospect will be used in long relief out of the bullpen, at least to begin his big league career.
The Astros used five relievers Wednesday night in a 7-5 loss to the Royals after starter Dallas Keuchel was scratched shortly before first pitch due to illness. Martes last pitched June 1 and could go multiple innings if needed.
Video: Martes records a strikeout for the Grizzlies
The Dominican Republic native has worked exclusively as a starter this season in the Pacific Coast League, but struggled to an 0-2 record with a 5.29 ERA, a 2.10 WHIP and 28 walks in 32 1/3 innings. Martes entered the campaign as the third-youngest player in the PCL, and his walk rate has jumped from nine percent with Double-A Corpus Christi in 2016 to a career-high 17.2 percent in 2017.
Despite those numbers, Martes' stuff could play up out of the bullpen. MLB.com gave his fastball a 70 grade on the 20-80 scale, noting that it typically sits in the mid-90s but can reach 98 mph, and graded his curveball at 65. Those two well-above-average offerings have helped the 6-foot-1, 225-pounder strike out 23.3 percent of the Triple-A batters he's faced.
Martes became the second top-100 prospect on the Astros' Major League roster. David Paulino joined Houston on May 30 and has posted a 4.66 ERA with 12 strikeouts in 9 2/3 innings over two starts.