Athletics' Sean Doolittle received PRP injection in shoulder

Athletics reliever Sean Doolittle received a PRP injection in his left shoulder, according to MLB.com.

Doolittle is expected to miss the start of the season due to the injury, but received in the injection in order to alleviate inflammation and irritation. Doolittle told reporters on Sunday that he feels a lot better than he did a month ago due to the injection. He's already started a strengthening program, but a timetable for his return is currently unknown. 

"Everything so far has gone really smoothly," Doolittle said. "We're optimistic, but we haven't set a timetable because, based on what the doctors and trainers have said, every issue is kind of different. With PRP, it's all about how your body reacts to it."

Doolittle posted a 2.73 ERA over 62 2/3 innings last season.