Question: Who is a former professional American football quarterback who broke his left hand and had a professional American football halfback replace him however he was relieved by Tittle in the fourth quarter of the game?  
Sentence (from "Y. A. Tittle"): Known for his competitiveness, leadership, and striking profile, Tittle was the centerpiece of several prolific offenses throughout his seventeen-year professional career from 1948 to 1964.
Relevant evidence: No