I love the analysis, but it doesn't feel quite right (not criticising, just a gut feel). Maybe it's the subtlety that replacing Gawn with a rookie (which definitely gets you increased $/pt) only leads to replacing rookies elsewhere with other premiums (which reverses the equation again). If the rookies you are taking out are really bad then it can be a clear win, but lets assume you've structured in such a way that you don't have completely rubbish rookies on field, and then it's much closer.
I've currently got Neale M1 and my M5 is Josh Kelly, so I'm happy I've got super-mids covered for captaincy options. Even so, I'll assume forgoing Gawn costs me 10-20 points a week in captain's scores, like you've said.
For the first 7 rounds maybe, a realistic on-field XvY is something like
Gawn, J Clark, FWD Rookie (135 + 75 + 55 = 265)
vs
Ridley, Dusty, Hunter (100, 100, 70?? = 270)
But give the Gawn team some bonus points for captaincy and it comes out ahead... so option 1 wins.
However, option 1 needs two upgrades (one from a mid-pricer), so lets assume 4 trades. Option 2 needs Gawn, so maybe three trades to get there. So option 2 wins on that front.
Option 2 carries more risk (rookie rucks on field), option 1 is safer (picking a consistently super high scoring SC player). So it's option 1 again.
So pretty line-ball call either way I think. Probably almost comes down to how happy I am with Jordan Clark after all that!
See the problem here is that you've added a variable to move the goal posts. Adding Clark and giving him scoring beyond his starting price is essentially adding a 3rd player so the first group can close the gap.
I mean I can take the same group and change the assumption so that Ridley and Dusty are both 115 players and all of a sudden the margin becomes 35 points a week to group B. Need to be very careful of creating scenarios to reinforce what you want to be true and muddying the original actual comparison.
Obviously at the end of the day we make 30 choices that are all essentially related to each other but that makes any rationale comparison impossible.
Ultimately, if you take a rookie instead of Gawn you've got ~620k to apply to the rest of your team. If you get fair value with that money, be it upgrading 6 low end premiums to high end premiums, upgrading one rookie to a premium, getting a back rookie off the field, picking a couple of midpricers, none of that really matters as long as you get fair value, the rookie over Gawn is going to be a more productive allocation of that first 124k if he averages as well as most would agree a ruck rookie will than Gawn at 140.
Totally agree with you on the elevated risk, it's really the only reason (I'd pay captaincy also) that starting Gawn and, to a lesser degree, Grundy even makes any sense, the ruck position with 1 bench spot and its isolation from other positions makes it a very risky area of the team to take chances.
Upgrading is also an issue, though there is obviously the case of if I take Neale instead of Gawn that I'm in the same end position, again if you've got fair value from that 620k you should be in the same position on this side of the coin. For mine the bigger issue with the upgrading is that the risk of the rookies compounds the longer they're in your team so you end you end up being forced to target the ruck upgrades which, as you said, can take a lot of trades, especially if Gawn does come out smashing 140 every week and with only two spots their relative value is just greater than other positions!
My personal focus is having to pick as few rookie defenders as possible and to field even fewer! I'd also love to pick Grundy, Gawn, Meek, Flynn and Hunter and have them all on the field though, the ultimate conundrum!