I have been thinking about how to incorporate a peak into my player career ratings. At this stage, my overall rating will comprise the career rating (70%) and the peak rating (30%).
I have come down to three options:
1. A 50-test peak
2. A ten-year peak (as done recently on the cricinfo IT figures blog)
3. A combination of the two (50 tests or ten years, whichever an individual player achieves first).
I think no.3 is the best bet, since no.1 would disadvantage players of older vintage, who played tests at a much lesser rate than players of today; and no.2 would disadvantages players like Botham, who had a peak of roughly 5 years, in which he played near enough to 50 matches.
btw, I used to think a 30-test peak was suitable, but I found it was too short a time period for modern players and didn't really separate the good players from the great ones (who should have longer sustained periods of peak performances).