Name the Prospects! Who were these guys?

Here’s a Sunday discussion question for you. I’m going to describe two pitchers who came to the major leagues at about the same time for the same team. You tell me who they were based on the descriptions.

PITCHER A: I am a left-handed pitcher who grew up in a cold-weather state. I was somewhat inconsistent but generally successful in the minor leagues, then jumped directly from Double-A (with no Triple-A experience) to the major leagues at age 21 for a rebuilding team. A starting pitcher, I was a slightly above-average pitcher for a terrible team for the first season and a half in the majors, using a low-90s fastball and a good curve. Pitcher B had slightly more strikeouts than I did, but my control was a little better. In my third major league season my career path changed drastically.

Who am I, and how did my career ultimately turn out?

PITCHER B: I am a left-handed pitcher who grew up in a cold-weather state. I was somewhat inconsistent but generally successful in the minor leagues, then jumped to the major leagues at age 22 with only a handful of Triple-A starts on my resume. A starting pitcher, I was terrible for the first season and a half in the majors, pitching for the same team as Pitcher A, who out-pitched me significantly. My strikeout rate was slightly higher than Pitcher A but his control was slightly better than mine. I used a low-90s fastball and a good change-up but had problems initially with my breaking stuff. In my third major league season my career path changed drastically.

Who am I and how did my career ultimately turn out?