Yahoo has been a little unpredictable regarding adding players to the database in the past. A few examples have already been mentioned. After a few snafu's in 07 (Braun, Lincecum and Gallardo all randomly FA) then 08 (MadMax, Kershaw, Price all waivers), but Votto and Bruce not our commish got an answer from the Yahoo team.
I can[t find it in my email.... but here is roughly what it said.
New players are added to the Yahoo database in SP IF there is a concensus (by whom, no idea) there is a high probability of player opening the year on the 25 man roster... for example: Jay Bruce in 08, and Wieters/Hanson/Zimmerman in 09. There is some-sort of cutoff date involved if I remember correctly.
If the player is not added to the yahoo database before the cutoff date, he is then only added once he is called up to the majors, and then his position is assigned based on (again assumption by Yahoo) what position he will most likely be playing at the MLB level. For example, Yahoo consider Clement a DH in 08, and James McDonald an RP upon his callup.
So you shouldn't see strasburg mysteriously/randomly added this year... he should go on waivers when he is called up in 09.
They also added a new league setting this year that overrides the "ST probability rule" so players are only added to the leagues database when the players actually makes the major league roster. If this rule is enabled by the GM, Wieters, Hanson and Zimmerman were not available on draft day. At least its consistant
If you found my advice helpful, please help me