HOUSTON -- Right-hander Taijuan Walker, the Seattle Mariners' top prospect, flashed his potential Friday night in notching his first career victory, a 7-1 decision over the Houston Astros at Minute Maid Park.
Walker (1-0) skillfully mixed an assortment of pitches that worked off a four-seam fastball that routinely hit 96 miles per hour. Ranked by MLB.com as the fourth-best prospect in baseball, Walker showcased that talent by stifling the Astros (44-90) throughout his five-inning stint, facing just four batters over the minimum.
The Mariners (61-73) supported Walker with a balanced attack. Excluding second baseman Nick Franklin and catcher Henry Blanco, each member of the lineup reached base via hit or walk. Center fielder Dustin Ackley finished 4-for-5 with four RBIs and also produced a spectacular sliding catch at the wall to cap the bottom of the fifth inning.
Ackley set a career high with those four hits and matched his single-game high for RBIs, set on May 4 against the Toronto Blue Jays.
Walker retired the first eight batters he faced before his defense stumbled and cost him an unearned run with two outs in the bottom of the third.
Mariners left fielder Raul Ibanez failed to make a leaping grab on a line drive that was scored as a double for Astros shortstop Jonathan Villar. Robbie Grossman followed with a routine grounder to shortstop Brad Miller, but Justin Smoak dropped Miller's throw at first base, allowing Villar to score from second and giving Houston a 1-0 lead.
Walker settled down and resumed a deft mix of upper-90s fastballs, cutters and disarming off-speed pitches.
Meanwhile, Astros right-hander Brad Peacock scuffled, allowing back-to-back RBIs to Ackley and Abraham Almonte in the fourth before Ackley chased Peacock with a two-run, two-out single to center in the fifth.
Peacock departed with two outs in the fifth and the Astros trailing 5-1.
Walker was lifted after only 70 pitches, having allowed one unearned run, two hits and one walk with two strikeouts in five innings.
NOTES: While Walker made his major league debut 17 days after turning 21, C Henry Blanco celebrated his 42nd birthday on Thursday. Walker was one month shy of his fifth birthday when Blanco made his big league debut on July 15, 1997, with the Los Angeles Dodgers. ... Walker and Almonte are the ninth and 10th Mariners to make their major league debuts this season. ... With rookie league Greenville clinching a postseason berth on Thursday night, five Houston minor league clubs are playoff-bound, including all four full-season affiliates.