My two personal favorites so far are Tank and/or Truck.
He has that nasty split finger that just falls right off the table. Like a dump truck.
Would enjoy brain storming some more suggestions here and settling on a nickname as a fan base.
That would be pretty sweet.
EX - Mike Mussina "Moose", Mariano Rivera "Mo", Hideki Matsui "Godzilla", Derek Jeter "Jete" etc.
You just know they are great because of the nickname attached to em.
That being said, Masahiro Tanaka deserves a nickname!