Walker was No. 1 in the right-hander rankings a year earlier, but such lofty positioning is of secondary importance now to the youngster from Yucaipa, Calif. The goal this spring won't be to maintain his prospect rankings, but to win a job on the Mariners' Major League roster.
Walker pitched well in three starts as a late-season callup last year, going 1-0 with a 3.60 ERA while allowing 11 hits with 12 strikeouts and four walks over 15 innings.
That brief taste in the Majors, along with similar exposure for rookie left-hander James Paxton, has both poised to challenge for rotation berths this spring when Seattle's pitchers and catchers report to Peoria, Ariz., on Feb. 12.
"It worked out well," general manager Jack Zduriencik said earlier this offseason. "Both with Taijuan and Paxton, neither one of them had to be on the roster this winter. But we decided it was in our best interest and their best interest to get them big league experience, so the whole month of September they traveled with the big league club and they each had a chance to pitch.
"We got them to pitch into September for the first time and they got a chance to face big league hitters and be around the big league club," said Zduriencik. "So the first time we break out of Spring Training, if both guys are on the club, they're familiar with a Major League road trip. They're familiar with a Major League locker room and throwing against Major League hitters. That's what we wanted accomplished, and in both cases, we did that."
Walker, the youngest player in the Triple-A Pacific Coast League last year, went 5-3 with a 3.61 ERA in 11 starts for Tacoma with 64 strikeouts in 57 1 /3 innings before his promotion to the Mariners. He opened the year in Double-A Jackson and went 4-7 with a 2.46 ERA and 96 strikeouts in 84 innings.
Paxton didn't rank among MLB.com's top 10 left-handed prospects, which came out Tuesday, but the 25-year-old southpaw was extremely impressive in his own September showings with Seattle as he posted a 3-0 record and 1.50 ERA in four starts while allowing just 15 hits with 21 strikeouts and seven walks in 24 innings.
Zduriencik said both can legitimately be viewed as challengers for rotation berths going forward.
"Absolutely," he said. "Are they going to be on the staff? That's up to what happens in Spring Training, obviously. But are they candidates, yes? We were very pleased with what we saw from both guys."