Pitcher or Batter

I have a younger friend at my school who needed some help. He is also a pitcher, he throws about average and can only really come out of the bullpen, he is 15, 5’7 and about 140, his fastball hits mid to high 60s, touching 70 on rare occasions.

He is wondering if he should focus more on batting or pitching. He has a solid power swing that is an essentially a produces line drives with carry his leg kick and swing is almost an exact copy of Josh Donaldson’s. He is good at taking pitches, but also whiffs a lot. He is fast but has bad fielding technique.

Which position would it be better to focus on, pitcher or hitter, or both?
If pitcher should he just focus at coming out of the pen?
If hitter, what position sounds best?

If he hits well, OF or 3B. If his fielding is not great then outfield. Never decide to be a reliever in HS unless you throw 95 or project to throw 95.