Few pitchers throw it. Anibal Sanchez throws something similar around 70 mph or slightly slower. Former Tigers right-hander Armando Galarraga would throw one slow, looping curveball per game in his first season as a Tiger, but soon got away from it.
Neither throws his quite as slow as Simon, whose slowest would obey the speed limit on most Interstate expressways. Though he seems to throw one per game, he threw three on Tuesday, the last registering at just 53 mph on the Comerica Park radar gun.
MLB.com's Gameday application classifies it as an eephus pitch, a throwback to the old-school gravity curveball for which Rip Sewell is credited with creating for the Pirates in the 1940s.