Wee Willie

How is Keeler a W power versus lefties yet has a 3-12 diamond on that side? Never seen a W with a diamond before, I assume that's some sort of mistake?
http://forum-365.strat-o-matic.com/archivesn/
http://forum-365.strat-o-matic.com/archivesn/viewtopic.php?f=12&t=529841