Hi mp,
there seems to be a bit of discussion about this in the forum at the moment. Mathematically there is no basis to think you will score lower in the early rounds with less Mid Prems in your team. It's how well you use the money that will determine that, not where you use it. It's definitely a swings and roundabout situation. Look at it in simple terms. If your bench has say $960k sitting on it, that means you have $9,040,000 on the ground. If we for arguments sake say you have 8 Rookies on the ground, that cost $1,240,000 and 14 Premiums/Midpricers that cost $7,800,000. If we put a random return on the rookies as say $2,700/point, and we know the other players started at close to $5,400/point (Let's pretend you have no discounted players like Beams or Thomas, just for the exercise). Then your scoring looks like this:
$1,240,000/$2,700 + $7,800,000/$5,400 = 459 + 1,444 (+120 for Captain) = 2023.
Surely everyone can see, it doesn't matter where, or how, you apportion the $1,240k and the $7,800k, Forward, Mid or Ruck, the equation is the same. This of course assumes everything is "equal" right now. Some will argue that some of the Mid Rookies will return at a higher rate, than say the Def Rookies. They may be right, but for the moment, that is speculation. (... and if they did, your tactic is better than the other peoples)
Without anyone going to extreme examples, just to prove me wrong, your first round and early scores are only dependant on how well you spend your money, not where you spend it.