Actually, because it is so hard at the moment to identify who the F5 and F6 will be come seasons end, I think it's best to develop your other areas first. At least you can have a bit of confidence in your trades there. I'd look to fix Caddy, probably to Lloyd. I don't like the idea of paying so much for NRoo. Let's compare NRoo and Swan, just for convenience sake, I know Swan mightn't fit your structure right now. They're both likely to miss a game or two between now and the end of the season, so let's call that part a tie.
NRoo has averaged over 110 4 times, in seasons 2006/7/8/9 he averaged between 117 and 113. I think it is too much to expect he can do that again. Let's give him a high expectation target of 110 this season, but realistically something in the 106-108 is more likely.
Swan is possibly in decline. 2009/10/11/12 were all over 120, and last year was 117. Let's say he crashes to that same 110.
Assuming they both miss 2 games, and play another 15 for the season, their totals will be 2,200 come seasons end.
NRoo has already scored 606, leaving him 1594 @ 106.3, with his price being $570.0k, each weekly point will cost you $5,364
Swan has already scored 462, leaving him 1738 @ 115.9, with his price being $521.0k, each weekly point will cost you $4,496
It really can be looked at as simply as, that you are buying points. It doesn't always meet expectations, but that is what we are doing. At the moment, the NRoo "expected" points are costing you 19% more than the Swan "expected" points. Why pay 19% more for something that is the same? NRoo points are worth just as much as Swan points in your team total. Buy your points as efficiently as you can.
Also keep in mind, you are not looking for the players that will fill F1-F6 for the season, you are looking for the cheapest Forward that will fill a F1-F6 position, from the time you trade them in! Yes, a "Zorko" might finish the season F6, but you are only interested in what his Ranking will be from the round you trade him into your team, until the end. It's no good trading him in to your team in round 7, and having him finish F6 for the season, if his last 16 games only see him rated F16 for that period of the season from round 7 to round 23.