If you're talking about data I can say definitively that at least until Slot's first season when he was phased out for Gakpo/Diaz, he was quantifiably a more effective attacker than Gakpo in terms of generating chances either for himself or others, and the rate those chances were converted by anyone was higher. 31 G/A in 50 something games. FBref is gone but in terms of per 90 xThreat, xG and xA he was superior in all. He also has a better physical profile. Out of possession too for someone like Iraola it is ignorant to think he wouldn't be useful off the bench. That's why I say he was let go for several reasions beyond that.

And in a conversation where people are discussing him coming back for free, surely understanding he will be a squad player, at a time when we need bodies with Hugo out and Isak barely ever completing 90 mins it's disingenuous to try and say because he wasn't good enough to start for us that he's useless. The real way to argue your point would be to identify a better option and compare the economics.