They share uncommon rookie success, powerful right arms and a proclivity for staying cool in the most intense moments.
Heading into Sunday's AFC championship game in Pittsburgh, some have even portrayed Flacco, the Ravens' quarterbacking prodigy, as the second coming of Roethlisberger, the pulse of the Steelers' offense and their unquestioned leader.
Does the comparison fit?
They might be kindred spirits, but they are not Xerox copies. Any similarity is based on first-year success, not freeze-frame replication.
Roethlisberger, 26 and nearly three years Flacco's senior, does some of his best throwing when he's on the move. Witness the play he made Dec. 14 to beat the Ravens here, scrambling left, reversing direction, then throwing a bullet to Santonio Holmes on the goal line.
Flacco often gets into trouble when he's out of the pocket. Most of his interceptions have come on sprints to the right, when he throws across his body. He is better running in that situation than throwing.
Roethlisberger, who has won a Super Bowl and gone to the Pro Bowl, sometimes holds on to the ball too long waiting for a play to develop, a trait that adds to his sack total.
Flacco has been trained well to read, react and dump, if necessary. Since training camp, he has made great strides in getting the ball out faster and protecting it better. His sack total reflects that trend.
"The Ravens have done a great job with Flacco," said Gil Brandt, a longtime personnel evaluator who works for NFL.com. "They don't ask him to do something he can't do. They don't ask him to take chances."
But does Flacco resemble Roethlisberger?
"Both have tremendously strong arms, and both are big guys who move a lot better than you think they would," Brandt said.
"Other than that, Roethlisberger didn't play quarterback in high school until his senior year because the coach's son was the quarterback, and this kid [Flacco] couldn't beat out the left-hander [Tyler Palko] at Pitt. My question is, where are those [other] guys now?"
For this season's two AFC finalists, the similarity is the road seldom traveled.
Roethlisberger, who came out of Miami of Ohio in 2004, won his first 14 starts his rookie season after taking over for the injured Tommy Maddox in Week 3. His first loss was in the AFC championship game to the New England Patriots.
Flacco won his first two starts in the NFL, is 13-5 overall and last week became the first rookie quarterback to win his first two playoff games.
"I think it's harder to come in today and play quarterback and have success than any other time, certainly than when I came in and when I left," Aikman, a Fox analyst, said on a conference call this week. "Yet we're seeing more and more young quarterbacks coming in and have varying degrees of success."
What impresses Aikman about Flacco is how he came to a veteran team, won over the locker room and emerged in his own right.
"I know the makeup of that team," Aikman said. "It's not an easy group to impress. And he's done that. When you're able to earn the respect of Ray Lewis and Ed Reed, that tells me he belongs."
Joe Douglas and Hue Jackson, two men who were influential in finding and then coaching Flacco, saw premonitions of that when they first met the quarterback from Delaware in what was formerly known as NCAA Division I-AA.
Douglas, the Ravens' East area scout, got the first tip on Flacco in the summer of 2007 from Mark Azevedo, a player personnel assistant assigned to cover the Colonial Athletic Association, in which Delaware plays.
Douglas watched Flacco play once on television, then made the trip from Owings Mills to Newark, Del., to meet him and see a practice. The meeting was as memorable as the practice.
"My first impression [was], 'This guy's definitely calm,' " Douglas said. "There's a certain confidence he has in his eyes that's hard to explain. He carries himself very confidently, but not arrogantly or cocky."
"He seemed to make every single throw, and you can see the ball jump out of his hand, the sheer velocity that he throws with," Douglas said. "I was trying not to seem excited, especially when I was standing next to another team's scout. It was definitely an eye-opening experience."
Douglas' next step was to bring Flacco to the attention of Ozzie Newsome, the team's general manager and personnel boss. From there, nearly every scout in the department watched Flacco and filed similar reports.
"The way the Ravens do things, all the credit goes to Ozzie because he trusts his scouts," Douglas said. "And I think we were fortunate to have some great offensive coaches who are able to harness his ability and bring Joe along. It's been kind of a perfect storm for Joe as far as coming to the right team."
Offensive coordinator Cam Cameron, along with Jackson, the quarterbacks coach, nurtured Flacco through a difficult training camp period when he was sluggish in the pocket and slow to make decisions.
When Flacco was forced to start, the coaches took a step-by-step, game-by-game approach and allowed him to evolve at his own speed. The progress has been remarkable. After throwing seven interceptions in his first five games, Flacco has thrown only five the rest of the way - none in the past four contests.
Jackson credits Flacco's intelligence for his assimilation of the ever-expanding offense.
"He's like a sponge," Jackson said. "If you tell him something, he has the ability to switch his thinking and move on to the next step. A lot of guys can't do that. He's a guy that can process information very quickly, recalculate it in his mind and then go and make the proper decision."
There have been bumps along the way. In the 13-9 home loss to Pittsburgh in December, Flacco completed only 11 of 28 throws for 115 yards with two interceptions. His passes were often high.
Jackson doesn't worry about that game's impact this weekend.
"If you look closely, [the high passes were] because he was getting hit," the coach said. "There was different type of pressure around him and different type of things going on. But in saying that, those are the throws he's got to make to take the next step. There are some plays he's got to make. I'm very comfortable and confident he'll make those. And he'll make them more times than he misses them."
BIG BEN VS. JOE COOL
............................. .. Age
26 (March 2, 1982) ..... 24 (Jan. 16, 1985)
6-5, 241 pounds ..... 6-6, 230 pounds
11th overall, 2004 ..... 18th overall, 2008
Miami (Ohio) ..... Delaware
........................Record as rookie
13-0 (regular season) ..... 11-5 (regular season)
............................Playoffs as rookie
1-1 (lost in AFC championship) ..... 2-0 (reached AFC championship)
..........................Rookie stats (regular season)
196-for-295, 2,621 yards, 17 TDs, 11 INTs ..... 257-for-428, 2,971
........................................ ................................................yards, 14 TDs, 12 INTs
RAVENS (13-5) @ STEELERS (13-4)
AFC title game
Sunday, 6:30 p.m.
TV: Chs. 13, 9
Radio: 1090 AM, 97.9 FM
Line: Steelers by 6