Whenever Neal and Manu play together, they were usually using Neal at PG and Manu stayed at the SG. I honestly can't remember a time w/ TP or Hill, Neal and Manu all in the game at the same time. I'm not saying it didn't happen, but I can't remember it. If they did, I'm sure the offense play calling changed to utilize two SGs at the same time to get max benefit and took the defensive hit for not having a true SF.
I'll be honest, I've never heard Manu say that but if you're sure it happened, then perhaps it is so. I'm no NBA coach but I do coach basketball and know the differences between positions.
Regardless of all that, let me ask you a question - if the SG and SF position are so similar in the Spurs system (or any for that matter) as you have mentioned, then why is there a need to delineate a position at all? Why don't we all just call them "wings" as you mentioned and forget about all the classification? Why did Pop say we needed a backup SF behind RJ if, according to you and Manu, SGs and SFs are the same?
Here's are two articles that mention Pop's need for a SF... I (and you) could probably find more
http://www.mysanantonio.com/sports/s...ell-697559.php
http://www.mysanantonio.com/default/...nse-734728.php