There is now “rookie” filtering in the leaderboards.
The criteria to be a rookie is any season where a player has started the season with fewer than 130 at-bats, and fewer than 50 innings pitched. Roster time is not a factor in these, so there may be the occasional player that show up that is not technically a rookie by MLB standards.
What’s neat is you can combine this with the “Multiple Seasons” feature to get the best rookies of any decade (or any time period really). For instance, here are the top rookie seasons by pitcher WAR since 1980.
And here are the top rookie seasons by batter WAR from 2000 to 2009.
It’s worth noting that if you don’t check the “split season” box, it will combine all a player’s seasons when they were rookie eligible and it will not “split out” the seasons.
Anyway, there’s lots of neat ways to filter this data and please let us know if you run into any bugs.