Dyche doesn't want his wingers on the byline. He wants them tucked in to prevent the other team from opening them up in transition. Whether Iwobi is capable of beating his man, getting to the byline and getting a cross in is sort of irrelevant.
Iwobi plays wing for Dyche because he works hard and defends. Same with McNeil. Neither gets to the byline, and both are much more dangerous in the middle of the pitch. They both play exactly how they're asked which is why they're always on the pitch when healthy.