At Eastern, he will be reunited with his former head coach at Camden Catholic, Rick Brown, now the Vikings' offensive coordinator.
Brown likes to spread the field, and Flacco has been helping his new teammates learn the offense.
Eastern, of course, faces an interesting situation because last year's quarterback, Anthony Gallo, returns. Gallo was also a first-team all-conference choice at linebacker and is one of the Vikings' true defensive leaders.
"Tom takes a little pressure off Anthony because it's very difficult playing 110-115 snaps a game going full speed," Eastern coach Dan Spittal said.
Spittal says there will be packages for both quarterbacks. That said, the 6-foot-1, 165-pound Flacco is expected to see sufficient playing time.
Flacco comes from a family in which he always tried to survive against his bigger brothers, but it has toughened him.
He is the third quarterback in the family. Besides Joe, his brother Mike, currently in the Baltimore Orioles minor-league system, was a starting quarterback in his senior season at Gateway.
His brothers John and Brian graduated from Audubon in 2010 and 2011, respectively. Both were two-way standouts, but neither played quarterback.
"Growing up, because of my brothers, I was always playing against older guys, and I think that really helped me," Tom Flacco said.
He doesn't seem fazed by the competition. Flacco straddles that fine line of being self-assured, but not overconfident.
"I have a lot I have to work on," he said.
His competitiveness isn't one of those things.
"With his four brothers, there is pressure when they have a Wiffle ball game," Brown said. "Tom is a competitor like the rest of them."
Flacco has made a favorable impression on his new teammates.
"Tom can make all the throws, and he has been a great addition," said Eastern receiver-cornerback Eli Woodard, among the top prospects in the junior class.
Brown doesn't want to put a future label on Flacco, but concedes that, if he continues his progression, he has Division I potential.
Flacco could have the same potential in baseball, in which he was a starting rightfielder for the varsity. Flacco also played freshman and JV basketball, an indication of his all-around athletic ability.
He joins an Eastern team attempting to rebound from last year's rare hiccup of a 1-9 season, but it won't be easy with a schedule that might be more unforgiving than last year's. Seven of this season's opponents were playoff teams last year, and many of them are expected to be improved.
Eastern has great football tradition. This is Spittal's 12th season, and last year was only his second sub-.500 campaign.
For the Vikings to compete against such a heavyweight schedule, Flacco will have to continue the progress that he showed as a freshman. And treat every game as if it's a Wiffle ball matchup at home.
Contact staff writer Marc Narducci at 856-779-3225, firstname.lastname@example.org, or @sjnard on Twitter.