Righthander Taijuan Walker, the Mariners' top prospect, won't throw for the next seven days after tests revealed inflammation in his right shoulder.
Walker, 21, had been expected to challenge for a spot in Seattle's rotation, but manager Lloyd McClendon now says it's unclear if Walker would be ready in time for the regular season.
“It’s a little bit of a setback, yeah,” McClendon told MLB.com. “But it is what it is and we just have to continue to move forward.”
Walker, who has been held back from the other pitchers since arriving in spring training with soreness, has been put on anti-inflammatories.
When healthy Walker, the 43rd pick out of Yucaipa (Calif.) High in 2010, has a fastball that ranges from 93-98 mph and usually sits at 95-96, but scouts consider the slider his best pitch. He has the raw ability to be a No. 1 starter, although the Mariners, of course, currently have one of the best in Felix Hernandez.
Walker reached the majors at the end of 2013, going 1-0, 3.60 in three starts.