Johnson was optioned to Triple-A Pawtucket after throwing a complete game shutout Saturday against the Mariners, Pete Abraham of the Boston Globe reports.
Johnson was dominant in his spot start Saturday, fanning eight hitters while not walking a single batter. However, with David Price set for his debut Monday, there simply isn't a spot in the rotation for Johnson at the moment. He'll head back to Triple-A for now, but Saturday's performance will make him a prime candidate for another spot start down the line.