daredevil To build and create through the left side, you need a winger who can either take on defenders 1-vs-1 or play deft combinations in the final third (ideally both). You need creativity from that position, like we have from Saka on the right, it's not just a matter of getting the LW service.
I don't think we need to sign a "transformative player" at the left wing, we just need someone who can actually be creative from that position, providing ball retention and penetration in tight spaces. Neither Martinelli nor Trossard really do that. Martinelli at his best is a relentless presser and amazing runner on counterattacks, but he struggles in tight spaces (and I don't think that will ever change). Trossard has popped up with crucial goals, but his general play is more limited, and he turns 30 in December (and is not an athlete to begin with).
I like Eze because he would add penetration and creativity to our team, provided his tendency to drift inside is managed/incorporated. He's less dynamic than Nico Williams but more intelligent IMO, a better decision-maker once he's beaten his man. He (or whatever other similar signing) may not be an automatic starter over Martinelli, but it gives you options and flexibility. City away, Martinelli starts. Porto away, Eze starts. For instance.