There was some concern before the team began activities this spring due to shoulder soreness. At the time, the team said it was "nothing serious," and it appears as though they actually meant it.
Of course, sometimes teams report a minor injury for a player and it turns into an extended stay on the disabled list, so Walker's positive bullpen sessions serves as reinforcement for the team's public optimism.
Seattle might still be looking at Ervin Santana or Ubaldo Jimenez, though. Their No. 2 starter, Hisashi Iwakuma has a strained tendon in the middle finger of his throwing hand, and the youth of the team's options behind him could be a concern.
Walker, 21, pitched just 15 innings at the major league level last season, but he appears to be in the running for the team's rotation this spring. He's been consistently mentioned was one of the top prospects in the game, and if he's able to put together a strong 2014 season, he could play a significant role in the Mariners' efforts to make a push in the highly competitive AL West.