Good point. You'd also want to guard against the seasonal anomalies. Maybe use last season's final standings (rookies would be zeroed) to determine some kind of weighted baseline, and then go by point totals on a four-week interval?
For example, say Jimmie Johnson finishes poorly in 2 of the first 4 races, and by seasonal point totals alone, should fall into the hypothetical "D" category (where he'd be an all-too-easy pick to improve from there) - but because of his championship season, you'd say that he could fall no further than "B", nor could any other driver in the Top 5 from the previous season. To go further, no driver who made The Chase could drop below a "C". So, you'd limit the relative ease of picking up a good/great driver who had just had a couple of bad outings, without inhibiting any of the potential upside of those previously less-accomplished drivers.
It would not only make your "C" picks (and thereafter) more important, but potentially even more rewarding (as they had a higher upside).
I could hardly be construed as even a casual fan (Junior fan, meaning, I typically only have to watch the first 10-15 laps of each race), and there's likely many things that I haven't considered in the above, but it's just an idea.
