Seattle's only other player ranked among the Top 100 is D.J. Peterson, who came in 88th overall and eighth among third basemen.
The annual ranking of baseball's biggest and brightest young talent is assembled by MLBPipeline.com Draft and prospect experts Jonathan Mayo and Jim Callis, who compile input from industry sources, including scouts and scouting directors. It is based on analysis of players' skill sets, upsides, proximity to the Majors and potential immediate impact to their teams. The list, which is one of several prospect rankings on MLBPipeline.com's Prospect Watch, only includes players with rookie status in 2014.
The Mariners had five players among the Top 100 in last year's preseason rankings, but left-hander Danny Hultzen (18th in 2013) dropped out of the list after undergoing rotator cuff surgery that will sideline him all of the upcoming season. Additionally, catcher Mike Zunino (23rd) and infielder Nick Franklin (47th) are no longer eligible after playing in the Majors long enough last year to lose their rookie status.
Left-hander James Paxton, who was 61st overall last preseason, didn't make the Top 100 this year despite pitching four strong games as a September callup for the Mariners.
That leaves Walker carrying the mantle for the Mariners' premier prospects, and he's again near the top of the charts, though moving down two spots after climbing to fourth overall in 2013. The hard-throwing 21-year-old is the No. 2 right-handed pitcher, behind only Archie Bradley of the D-backs, who was fifth overall. Twins outfielder Byron Buxton was the top-rated overall prospect.
Walker pitched extremely well in his three starts for Seattle last year, going 1-0 with a 3.60 ERA while allowing 11 hits with 12 strikeouts and four walks over 15 innings. The native of Yucaipa, Calif., was the youngest player in the Triple-A Pacific Coast League last year, posting a 5-3 record and a 3.61 ERA in 11 starts for Tacoma, with 64 strikeouts in 57 1/3 innings before his promotion to the Mariners. Walker opened the year with Double-A Jackson, and he went 4-7 with a 2.46 ERA and 96 strikeouts in 84 innings.
Peterson, 22, cracked the Top 100 for the first time after being selected 12th overall in the first round of the 2013 First-Year Player Draft out of New Mexico. The young third baseman hit a combined .303 with 13 home runs and 47 RBIs and a .918 OPS in 55 games between short-season Everett and Class A Clinton before being sidelined by a broken jaw when he was hit by a pitch in late August.
Peterson has fully recovered now and will report to the Mariners' Minor League camp for an early minicamp on Feb. 15 in Peoria, Ariz.
Walker is on the Mariners' 40-man roster and will report to Major League camp with the rest of the pitchers and catchers on Feb. 12.
Based on rankings that award 100 points for the No. 1 overall prospect, 99 for No. 2 and so on down the line, the Mariners had the most "prospect points" of any Major League team last preseason with 351. But with just Walker and Peterson on this year's list, they fell to 20th among the 30 MLB teams with 108 points.
The Astros compiled the most prospect points this preseason with 439, three ahead of the Red Sox's 436. Boston had the most players in the Top 100 with nine, followed by the Astros and Cubs with seven each.