Yeah...you did say "professional football", right?
Long before the 2007 New England Patriots and the 1972 Miami Dolphins, perfection in pro football was first achieved by the Browns.
Paul Brown's creation produced a 15-0 championship season in the All-America Football Conference in 1948.
he 1948 Browns were the third of Paul Brown's four consecutive AAFC championship teams. Spread across the 1947 through '49 seasons, the Browns had an unbeaten streak of 29 games during which they went 27-0-2.
http://blog.cleveland.com/sports/2008/02/browns_put_together_a_forgotte.html
Long before the 2007 New England Patriots and the 1972 Miami Dolphins, perfection in pro football was first achieved by the Browns.
Paul Brown's creation produced a 15-0 championship season in the All-America Football Conference in 1948.
he 1948 Browns were the third of Paul Brown's four consecutive AAFC championship teams. Spread across the 1947 through '49 seasons, the Browns had an unbeaten streak of 29 games during which they went 27-0-2.
http://blog.cleveland.com/sports/2008/02/browns_put_together_a_forgotte.html
