Prospect of the Day: Taijuan Walker, RHP, Seattle Mariners

Seattle Mariners top prospect Taijuan Walker took the big league mound for the first time in 2014 yesterday, throwing six innings against the Houston Astros, allowing five hits, two walks, and three runs, fanning six and collecting the victory. Walker scared the heck out of Mariners fans (and fantasy owners) with arm trouble earlier this year, but he's healthy now and ready for an extended major league trial.

Walker was drafted by the Mariners in the supplemental first round in 2010, from high school in Yucaipa, California. Signed for $800,000, he was considered extremely projectable but rather raw at the time, given that he was mostly a basketball player and shortstop in high school. He looked good in seven feet-wet innings in rookie ball that summer, fanning nine, then moved up to full-season Clinton in the Midwest League in 2011. He posted a 2.98 ERA in 97 innings, with a 113/39 K/BB ratio and only 69 hits allowed. Midwest League sources noted that he looked a lot more polished than they had expected.

The Mariners jumped Walker to Double-A in 2012. The youngest pitcher in the Southern League, he struggled at times and posted a 4.69 ERA for Jackson, but he generally acquitted himself well considering the circumstances, posting a 118/50 K/BB in 127 innings. Returning to Jackson to open 2013, he posted a 2.46 ERA with a 96/30 K/BB in 84 inning with just 58 hits allowed.

Promoted to Triple-A Tacoma at the end of June, he posted a 3.61 ERA in 11 starts with a 64/27 K/BB in 57 innings, allowing 54 hits.He made three big league starts last year and looked good, with a 3.60 ERA and a 12/4 K/BB in 16 innings.

He was expected to be in the Mariners rotation this year but was slowed early by a "shoulder impingement," which sounds scary. He worked through it however and has been effective in rehab outings, posting a 4.11 ERA with a 29/10 K/BB in 31 innings for Tacoma. This included a nine-inning complete game shutout with eight strikeouts on June 24th, which convinced the Mariners that he was all the way back and set the stage for yesterday.

Walker is a 6-4, 230 pound right-hander born August 13, 1992. As you can imagine given his amateur background, he's an excellent all-around athlete who took well to mound work once he moved there full-time. His fastball has been clocked as high as 98 MPH and fits comfortably in the 93-95 range most of the time. Unlike many young power pitchers, he commands the fastball well and hits his locations, not relying on just pure velocity to blow people away.

The key for Walker has been steady development of his secondary pitches. He has a slow curveball, a harder slider, and a traditional change-up to mix with the heat. The curveball was erratic early in his career but has improved greatly over the last 18 months. His change-up remains his weakest offering but has improved. At his best, when all four pitches are working, Walker can hit any velocity slot between 70 and 98 MPH.

Walker's makeup is considered a positive; he's bright, confident, works hard, and is considered to be mature for his age. Command of his secondary pitches is still inconsistent at times but Triple-A hitters no longer exposed this. What he needs to learn he can only learn against major league hitters at this point.

Walker has everything needed to be a top-flight starter. We just need to see if he can stay healthy.