In my opinion Martinelli is one of the best left wingers in Europe. I struggle to name 5 better left forwards currently and wonder what else people are expecting from him. He's playing the system how he's been asked to and sacrificing a lot of himself for the overall team shape by staying so wide so often.
There's a reason why Arteta loves him so much even though he's not getting as many goal scoring opportunities as he did last season due to the change in shape. I'm 100% sure had we been playing to his strengths he'd score a bucket load. He's one of the last players I'd replace after the 2 CBs, Rice, and Saka.
Think he'd probably get into any team in Europe not named Madrid and maybe PSG if Mbappe is still playing on the left.