Career High On Base Percentages
Ted Williams holds the career record for On Base Percentage (minimum 5,000 plate appearances) with .482. Mickey Mantle holds the career record for OBP (minimum 5,000 PAs) for switch-hitters with .421.
In case you’re wondering, the leader among active players, Todd Helton (over 7,000 PAs) has a career OBP of .419. As for switch-hitters, Lance Berkman (over 6,000 PAs) leads active players with a career OBP of .409.