Perhaps it's easier if we use generalities?
For example, looking at Total Offense and Total Defense stats, instead of individual players, and seeing how long until they jived with end-of-season rankings?
The '05 worst 10 defenses, in order from worst to 10th-worst, were: SF, Houston, StL, Buf, Cin, Oak, NE, KC, NYG, and Philly.
Preseason '06, the bottom defenses may have been rated (not sure, exactly, but reasonably): Oak, Hou, SF, SD, Cin, Ari, Cle, GB, Det, StL.
YTD in '06, they are, in ascending order: Hou, GB, Ten, NYJ, Ari, NYG, Det, Cle, SF, and Cin.
Some teams, like the Giants, are in the bottom tier of Defense, but is this due to them being a bad D, or due to them having had to face Peyton, McNabb, and Hasselbeck in their first 3 games? Should the Giants be downgraded from a preseason 10-15th best to a potential bottom 10? Is Oakland, which ended '05 at the bottom, and was ranked near the bottom before the season started, an upstart D or have they just been lucky the first few weeks, facing Cleveland, Baltimore, and San Diego's offenses?
At about which week, historically, would Total Defense-YTD most likely represent end-of-season numbers? And is it a similar point in the season for Total Offense-YTD?
And, in terms of fantasy, when can I start using YTD Total Offense and Total Defense numbers to project the matchup for my players--when do '06 YTD stats better reflect "reality" than preseason projections? Should I be avoiding starting QBs vs. Oakland, since they're now top-10? Should I prefer starting my QB vs. the Giants?
I think that doing the analysis with these generalities may be easier than analyzing Player X's situation specifically.