dlrawson is correct. You MUST use the first season that is $5 mil + UNLESS you opt for a cheaper earlier version for the player to begin with.
So if you drafted Yaz, I would asume you would start him off in 1962 unless you opted to start him as the 1961 season. Drafter's choice. That would then become the players "Born into the League" Season. We would list him on the Draft board as 1962 unless you posted or decided otherwise. Just let me & the League know your intentions are sometime before the season starts.
It's not stipulated yet in the League Rules- I will add this clause as well for Pitcher / Hitters. I think the Drafter should be able to choose at his discretion if he'd like to start the players as a hitter or pitcher-- i.e. Babe Ruth.
Ruth the pitcher would be "born into the League" beginning in 1915- his first WIS pitcher season @ $8.7 mil.
Ruth the hitter would be "born into the League" beginning in either 1918 ($4.3 mil) or 1919 ($8.4 mil)
Another choice for the Drafter is starters/relievers. For example Dennis Eckersley.
Eck can be drafted as a Starter and can be "born into the League" beginning in either 1975 ($4.8 mil) or 1976 ($5.5 mil).
OR Eck can be drafted as a Reliever in which case he would be born into the League" beginning in 1987 ($3.7 mil).
The $5 mil & $3 mil are just benchmarks to be sure that every drafted player can make a legitamate contribution as a full time player rather than field a team of guys early in the careers that can't hit or pitch for 3,4, or 5 years. The lesser salaried earlier seasons are simply options.