The metric is an important one. The effectiveness of a winger is best indicated in their output, and his output is and has been poor his entire career.
Of course there are other things that go into it, but my whole point was that based on what we know from his career and have seen whilst he's been with us, we have very little evidence that he'll be a good winger worthy of starting in that position. Even though he hasn't started as the winger, we've seen him in wide positions since he's been with us and hasn't done much. We haven't seen him burst past players, beat them in one-on-ones, put consistently good balls in etc. We've seen him enough to have a good idea of his attributes, and I think it would be disingenuous to suggest what we've seen from him in any way suggests he'll set the world alight on the wing.
You can't say that just because we haven't seen him specifically start in that position then we can't have an opinion.