For someone who demands ridiculous high standards for Barca players, this one is difficult to comprehend.
Not a fan of current Lewa, but you can still see remnants of his elite finishing. Ferran, for everything else he offers, doesn't have it in his locker. If you want to hold down the position of a starting striker at a top club, you need to exhibit top-class finishing. That aside, there isn't one attribute you could say is elite. His off-ball movement and pressing is good but attributes like first touch, speed, airial game, and decision making is mid. Nothing special about him in any dept. He's thriving under Flick's system but will get exposed under a more control based technical set-up.
Ergo, Barca deserves a better starting striker.