Triple-A Worcester transferred Walter (shoulder) from its 7-day injured list to the 60-day IL on Wednesday.
Walter possesses a spot on the Red Sox's 40-man roster, but he's currently residing on the Triple-A club's IL since he was optioned to the affiliate in early March. He strained his left shoulder toward the end of camp and has yet to pitch for Worcester. His season debut now doesn't appear as though it'll come until at least June as a result of his move to the 60-day IL.