I've got two 19 y/o prospects, each of which should have a shot at being all star level major leaguers.

Banjo Kline played 18 ST games.
Rymer Tabaka was only on the ST team one day and played one game because I somehow forgot about him when adding prospects to the squad. Each gained exactly the same amount of ratings (except Banjo got one more base running point, Tabaka is probably near his ceiling in base running anyway).

Maybe Tabaka gets a few more 2 point bumps in some hitting categories if I had played him more games, will never know. Was also expecting Kline to have more than one rating get a two point bump.

Thought I would share in case anyone was interested.