You've probably also heard that the upcoming film, "Unitas We Stand," has generated mixed reactions from the Unitas clan, with Johnny U's grandson, J.C. Unitas, calling the Baltimore Ravens quarterback an "embarrassing choice" for the role.
Flacco -- no stranger to criticism -- says he's honored to play the former Baltimore Colts great.
"This really was the fact that this is Johnny Unitas, and he's one of the greatest quarterbacks that has ever played," Flacco told the Ravens' official website. "It's just one of those things that comes along and I was honored to be the guy that was asked."
Flacco, who never met the Hall of Fame passer in person, will depict an under-the-helmet Unitas in scenes showing Baltimore's 1958 championship game against the New York Giants (aka "The Greatest Game Ever Played").
"I'm just excited that I get to go out and put on some kind of Johnny Unitas uniform and go out there and run around a little bit," Flacco said. "I'm a little nervous about the fact that I'm probably not going to replicate him perfectly. I don't know if they're going to want me to go out there and just look like me, or if they're going to want me to actually look like him a little bit."
(Our guess: Like him a little bit.)
Follow Marc Sessler on Twitter @MarcSesslerNFL.