Read this one Spider Klein
Its comparing picking the top scoring player (Rocky) as captain compared to J.Selwood in this case.
This year based on Magic Number the avg starting point for all your players is 1766 points (Salary / Magic Number). - this isnt including captain.
J.Selwood as Captain maintaining avg (106)
1766 - 106 = 1660 (Is the total amount of points the rest of the team scores W/O J.Selwood)
1660 + 212 (2X captain score, in this case 106 which is 212) = 1872
Rockliff as captain maintaining avg (134)
1766 - 134 = 1632 (Amount the rest of Rockliffs team scores, as you can see less than J.Selwoods because J.Selwood is cheaper and more can be spent on the rest of the side compared to Rockliff)
1632 + 268 (2 x captain score of 134 = 268) = 1900
I definitely get what you are saying here, but there are also price fluctuations that come. The reality is that it will be exceptionally difficult for Rockliff to maintain his current price. He has to be at least as good as his stellar year last year.
I will be getting Rockliff, but not at his current price as I think he will come down. I'm also concerned they will have him play more as a forward which might impact his points.
Anyway here is another discussion on mid-priced players and rookies.
http://www.unambitiousus.com/sports/afl-fantasy-2015-mid-priced-rookie-midfielders/