Prospects get the call: Taijuan Walker

Aug 30, 2013; Houston, TX, USA; Seattle Mariners starting pitcher Taijuan Walker (27) pitches during the third inning against the Houston Astros at Minute Maid Park. Mandatory Credit: Troy Taormina-USA TODAY Sports

The latest in a flurry of prospect promotions over the last 24 hours, the Seattle Mariners will call up Taijuan Walker for tomorrow’s game against Houston, MLB.com’s Greg John reports.

Prior to the season, Walker was expected to break camp with Seattle, but the 21 year old was sidelined by a shoulder injury. The 5th best prospect in baseball has spent the last month of the season on rehab assignment with Triple-A Tacoma, during which time he has a 4.11 ERA, a K/9 of 8.5 and a BB/9 of 2.9 over six starts.

Speculation for a promotion has been mounting since Walker’s last Triple-A start. Facing the Oklahoma City Redhawks, Houston’s affiliate, the young right hander was in complete control, throwing a complete game four-hit shutout, the first of his professional career. He struck out eight and surrendered but one walk.

This will not be Walker’s first exposure to the major leagues. He already impressed in a cup of coffee at the end of last season, with a 3.60 ERA and 12 strikeouts in 15 innings.

Although Walker has number one starter stuff across the board, he has always stood out more for his makeup, pitchability and poise on the mound. Scouts are not so impressed by the fact that he has a 97 MPH, but by the ease with which he throws it.

“A lot of things come so easy to him,” Mariners catcher Mike Zunino told Jeff Passan last fall “It’s his athleticism, his maturity. He just turned 21, and he’s handling himself really well here.”

The athlete – he was also a standout shortstop and basketball player in high school – also throws a change-up, a curveball, and a cutter that some call a slider, all of which are major league quality and have a chance to be above-average offerings. Although the sample size was small, Walker relied primarily on his fastball and cutter in his major league stint last season, throwing them a combined 85% of the time according to Fangraphs.com.

Control was basically the only knock on him but the former first round pick seems to have improved in that department of late. His 2.9 BB/9 this season in Triple-A was the best of his professional career.

To make room for Walker, the Mariners have optioned rookie outfielder Stefan Romero to Triple-A. The 25 year old rookie has struggled mightily this year, hitting a paltry .200/.240/.331 in 50 games for eattle