For those still concerned about this argument, here would be how you could make a case for Manu over Carter.
Carter's 24.6 ppg this year come on 19.5 shots, which means he scores 1.26 points/shot. They also come with Carter playing 38.5 min/game, which comes out to .639 points/minute. He also averages 6 rebounds and 4.5 assists per 40 minutes, with a Hollinger PER of 20.46.
Manu averages just 16.3 ppg, but they come on only 11.6 shots, meaning he scores 1.405 points/shot, a higher rate than carter has. He also scores these points in just 27.9 min/game, which comes out to .58 points/minute, while taking many fewer shots. His 40 minute averages of 5 rebounds and 5.2 assists per 40 minutes compare at least equal to Carter's, and his PER of 20.93 is higher. Manu also averages .7 steals/game more than vince, in nearly 11 fewer minutes.
Manu is more effective per minute, and scores more efficiently. Carter scores more, but takes many more shots, though he can play more minutes per game. The point is, there is an argument that can be made for Manu over Carter, and not just based on homer-Spurs logic.