Seattle Mariners right-hander Taijuan Walker began the 2013 season back in Double-A Jackson where he spent all of 2012 because he needed to improve in several areas and the club correctly deemed the Southern League as the best place for him to take on such tasks. Tuesday, the 20-year-old showed how far he’s come in only four months and why he’s among the very top pitching prospects in all of baseball. Walker, a sandwich-round selection in 2010 (No. 43 overall), used his stuff, poise beyond his years and a maturity level necessary for the circumstances to toss six shutout frames at the Fresno Grizzlies, allowing three singles and two walks, while striking out four. He threw 87 pitches, 56 for strikes, and for all 87 he appeared to be every bit the phenom he’s been cracked up to be since he burst onto the scene three summers ago as a raw 17-year-old. The 6-foot-4, 210-pound Walker featured a four-seam fastball that sat 93-95 mph and touched 97, and came to the plate with ferocious downward plane, creating a very heavy ball, one extremely difficult to square up for hitters. He commanded the pitch down all night, missing only below the zone, not up, with some occasional arm side run and natural sink. He worked his 90-93 mph cutter in often, helping set up a much-improved 71-74 mph curveball that froze batters all night. He sawed off several bats with the four-seamer and cutter and used the curveball with two strikes or to keep the Fresno lineup off balance. He tossed a half-dozen or so below-average changeups in the mid-80s, but kept it down or away from left-handed batters and one in particular showed some fade, though each lacked sink. He maintained good arm speed on the pitch, but it’s still a ways from being more than a show-me offering. Walker’s velocity didn’t dip much from the stretch — he sat 93-94 with runners on — and did not let some bad luck get to him. There were 4-6 borderline pitches on which he did not get the call from the home plate umpire, but he went back to work, rather than allowing it to get to him and affect his approach. The four-seamer induced ground balls and the cutter forced poor contact that resulted in shallow fly ball outs and pop ups, and he did miss some bats with both pitches. His curveball is a full grade better today than in spring training or at any point a year ago, and he’s taken well to the cutter and seems to know how to use it. Walker’s delivery was very consistent with one exception: He drops his arm slot slightly and opens up early on the curveball, which could be an issue against better hitters and it’s something he’ll need to fix for general consistency purposes, if nothing else, but big leaguers will see it and exploit it. Walker’s velocity comes free and easy without much effort, which bodes well for his ability to hold that velocity deep — which he did through pitch 87 Tuesday and has done through the low-100s in the past — and if his high three-quarter arm slot can be maintained with the curveball, there’s no reason to believe he won’t max out and become a No. 1 starter. There may even be ace material here, though we’re likely a few years away from that kind of command from Walker. I came into this start with one objective, which was to remain as objective as possible. Even doing so, it’s difficult to suggest Walker is on a path that will lead to anything but future stardom. That isn’t likely to occur in 2013, and while he’s likely to see the big-league mound in 2014, he may not settle in and succeed at a high level right away. His stuff, athleticism and his apparent acumen for progress may prove me wrong there, however. He was very crude coming out of high school and in less than three years has gone from high-upside project to elite pitching prospect on the doorstep of the majors. He’s raised the ceiling on all of his grades since then — here’s my 2010 draft-day scouting report on Walker for subscribers — and now the sky is the limit. After four innings, M’s scouting director Tom McNamara tapped me on the shoulder. I looked back and he gave me a look as if to ask, “so, what do you think so far?” My response? “I’d be excited if I were you.” Taijuan Walker is a phenom, and it may not be long before he’s toeing the rubber at Safeco looking to back up a Felix Hernandez gem with one of his own.Go!

A B C D E 1 NO. PLAYER POS AGE LEVEL 2 1 Kyle Lewis RF 23 A+ 3 2 Noelvi Marte 3B 16 NA 4 3 Logan Gilbert RHP 21 NA 5 4 Julio Rodriguez RF 17 DSL 6 5 Evan White 1B 22 A+ 7 6 Damon Casetta-Stubbs RHP 18 NA 8 8 Sam Carlson RHP 19 NA 9 7 Josh Stowers CF 21 SS-A 10 8 Braden Bishop CF 24 AA 11 10 Cal Raleigh C 21 NA 12 11 Juan Querecuto SS 17 DSL 13 12 Bryson Brigman SS 23 A+ 14 13 Luis Liberato CF 22 A+ 15 14 Daniel Vogelbach DH 25 AAA 16 15 Rob Whalen RHP 24 AAA 17 16 Art Warren RHP 25 AA 18 17 Seth Elledge RHR 22 A+ 19 18 Matt Festa RHR 25 AA 20 19 Joe Rizzo 3B 20 A+ 21 20 Wyatt Mills RHR 23 A+ 22 21 Joe DeCarlo C 24 AA 23 22 Jansiel Rivera RF 19 SS-A 24 23 Anthony Jimenez OF 22 A+ 25 24 Johendi Jiminian RHP 25 AA 26 25 Ronald Rosario RF 21 SS-A 27 26 Michael Plassmeyer LHP 21 SS-A 28 27 Joey Gerber RHR 21 SS-A 29 28 Eric Filia LF 26 SS-A 30 29 Max Povse RHP 24 AA 31 30 Holden Laws LHP 18 NA 32 31 Joe Rosa 2B 21 A 33 32 Ian Miller CF 26 AAA 34 33 Osiris Castillo SS 17 DSL 35 34 Brayan Perez LHP 17 DSL 36 35 Donnie Walton 2B 24 AA 37 36 Ryne Inman RHP 22 A 38 37 Luis Veloz OF 18 DSL 39 38 Jake Anchia C 21 SS-A 40 39 Joey O'Brien RHR 20 SS-R 41 40 Arturo Guerrero OF 17 DSLGo!