The 'fair test' of this would be to take a the same players and see results playing both ways for a significant chunk of the season, ideally for a whole season each. This is difficult to do, if not impossible, then all you can do is compare what is happening in general or has happened. Redknapp essentially employed conventional wingers, albeit you might say they were in top form, and our goals, style and, more importantly results, I expect were better.I'd love to see some data to support that less chances are created with inverted wingers than conventional ones. If you could find some, you might just convince me that you are right.
I haven't got actual stats, but it seems more logical based on what I surmise.
Another way might be to count how many goals are scored and how the chance was made, for all teams, say this season?