Yuki Matsui was slowed by left shoulder tightness during spring camp this year. He recently told reporters that his fastball was lacking polish because he was unable to do enough throwing before the start of the season.
Matsui has had to change his approach to make up for the difference. He has been throwing more sliders than change-ups because he feels there is not enough of a difference between his fastball and change-up. He is also throwing more cutters as well, a pitch he started using in September last year.
Matsui is hoping to be at 100 percent by the summer.
Source: Nikkan Sports 4/12/2016