I can only speak about what he was good at in Bundesliga. There he was a good finisher, excellent aerial threat, master of simple dribbling, quick decision maker. Basically a direct output oriented attacking Allrounder. In Bundesliga he could have become anything l. Flick thinks of him as long term striker partner for Adeyemi. In PL, best I can think of is someone in the firmino mould.
he will never be as effective here as in a less physical league unless he puts On a good 10kgs of muscle. He just can’t keep hold of balls into space which is what he needs for his game. In fact he will remain a peripheral figure irrespective of his talent as long as he does not improve physically and also gets tougher mentally