Claudius as has been mentioned in this thread, I think that's not a totally fair comparison based on the relative teams/circumstances they are in. Additionally the aspect I liked about Williams was his directness his ability to try and take on and beat defenders to pull them out of their set lines and take some of the attention off the right flank and Saka. I think something like that could be a major uplift even if the goals output from them individually might not always be great.
I'm not saying Williams is a guaranteed thing but your going to have to take a chance on those types of players with the right age profile and assess them to try and mitigate as much as reasonable how you value them but we aren't going to be competing with the top tier "as near guaranteed players" so we will need to do that kind of business.
Looking at martinelli over the past 2 seasons I don't think he would be on the list for players I would feel were going to help us take that step to the title if he wasn't at arsenal.