Mariners right-hander Taijuan Walker was scratched from Tuesday's scheduled Triple-A start with what is being called arm stiffness, reports Bob Dutton of the News Tribune. The team's top prospect missed time in spring training and the start of the season with a shoulder problem.

Walker, 21, had trouble getting loose during his pregame routine, according to Dutton. He was scheduled to throw 90 pitches in what would have been his third minor league rehab start.