Nolan Gorman is expected to man the keystone most of the season, but his defensive shortcomings could necessitate him to serve as the designated hitter for several games. He'll have competition for that role, as Juan Yepez and likely eventually Jordan Walker will also earn reps at the position. Paul DeJong could see time at this spot as well after losing his starting shortstop role to Tommy Edman last season.
Prediction: Yepez will earn most of the starts at designated hitter. His fielding is far below average, and he has shown he is a dangerous hitter. Walker and Gorman are too young for them to be pigeonholed as frequent designated hitters, and while DeJong could bounce back this year, I can't see him receiving much time at the position early in the season because of his struggles the last two seasons. He'll need to prove himself.