Don´t know too much of Gk as you. But i think he can better in DEF, even he is still very young and a huge growth gap - he has a very good positional sense, maybe in crosses and corners isn't too safe but has decent control of "penalty area", also considering he hasn't more 1vs1 stopper card/star and his low TW value that works together with DEF. I saw him 1-2 points higher. The best and most known example for other users, is the game against Barcelona, if he wasn't show that good positional sense and covering angles, Leverkusen probably had lost 10-1 (same as SportFreunde Stiller song
), and as a regularly Leverkusen follower that shows every single weekend. No doubt that his main attribute is his responsiveness.