Agho has always been good at sharing the ball. I'm not worried about it.
If Agho is consuming anywhere near 25% of the offensive possessions then Columbia could have a problem but I don't think that is going to happen. If Agho's possession % slides down to the 20-22% range and he is taking higher percentage shots then he should be an asset. This is what I'd expect.
Also Agho won't be subtracting from Barbour's possessions so much as taking away possessions consumed this year by Johnson and Crockett. Sliding Rosenberg over to PF - the real problem position - would also mean erasing Daniels' possessions for Agho possessions.