Justin Masterson has been in the big leagues for only seven starts now.

No one doubts that the rookie right-hander has the stuff and the maturity to become a winning pitcher in the majors.

The key for him, though, is to make sure he has a good sinker to go along with a sharp slider. If Masterson is getting a lot of ground-ball outs, he’s on his game. and If the ball is up, his success is going to be more problematic.