Mariners' Sam Carlson: Held back in extended spring training

Carlson is being held back in extended spring training, MLB.com's Mike Rosenbaum reports.

He is not dealing with any known injury, so this is likely just a situation where the Mariners don't think the 19-year-old is quite ready to get full-season hitters out. Carlson could be assigned to Low-A in the coming months or the team could wait until June to assign him to a short-season league.