premise: Mosiula Mea'alofa "Lofa" Tatupu (born November 15, 1982) is a former American football linebacker who played six seasons in the National Football League (NFL). He was an assistant linebackers coach with the Seattle Seahawks. He played college football for the University of Southern California (USC). Tatupu was drafted by the Seattle Seahawks in the second round of the 2005 NFL Draft.
hypothesis: Tatupu retired before his 28th birthday. 
reason: It is not stated whether Tatupu completed his sixth season. He could have retired mid-season before his birthda . 