From Blaseball Wiki
Patient is a Player Modification, first seen between Season β21, Days 71 and 72.
Whenever a Player with Patient is batting, there are zero strikes, and they are one ball away from a Walk, the player will never swing.
As a result of the Library, the Antarctic Fireballs were revealed as having joined Ultra League Blaseball during Pre-History I, which also revealed their roster to the Fans.
Fireballs batter Lenny Watson had the Patient modification when they were revealed, and it has never been seen as an active Player modification.