Well a narrow victory requires less changes, and less implausible ones : Béhuchet let some autonomy to genoese commanders, Flemish fleet react more slowly to wind's change.
So, if you go for plausibility, take this one : a delayed Plantagenet raid would be interesting and certainly would change enough of early HYW to make a good TL.
A crusing victory is, safe out-of-character actions, implausible. French-Geonese fleet doesn't have the place to manoeuvre and wouldn't have the same motivation to crush Anglo-Flemish one, simply because they're on defense.
So, for the sake of discussion, let's assume that we're talking about the first :
- Anglo-Flemish dominance on Channel is somewhat threatened but not clear result. A Sulys-equivalent battle would happen sooner or later for that either French or English could invade each other.
- It gives more room and time to Capetians to act : probably more war effort in Gascony. Maybe (but I doubt it, or at least its efficiency, in Flanders at some time).
It could really evolve either in another Plantagenet campaign in France, or in a French campaign in England, both of them having equal chances to fail or success. Sulys was a decisive battle for Plantagenets, not for Capetians.