A year ago, the Chargers had worked him out at his college Miami, Oh. They were impressed with him back then.
As a rookie, he went undefeated in the regular season, leading the Steelers to a 15-1 record. They would bow out to the eventual Super Bowl Champion New England Patriots in the playoffs.
But he poses matchup problems for the Bolts in a variety of ways.
"You can turn a guy loose on him and they bounce off him," head coach Marty Schottenheimer explained. "He is a giant, particularly for the position he plays."
A former high school tight end, Roethlisberger stands 6-foot-5 and weighs in at 245 pounds.
He is the sixth biggest guy on the Pittsburgh offense. That means other than the five offensive linemen, Roethlisberger has the most meat on his bones.
"Tackle low or you will be embarrassed," linebacker Donnie Edwards said. "This is a guy we have to contain and bottle up."
But for his size he has a unique ability to scramble and adapt on the fly. While he has not thrown many passes, he has made them count.
And the scary part is how he has absorbed from a year ago.
"I understand our offense better and understand opposing defenses," said Roethlisberger. "I can decipher which guys are going to be open against other defenses. Last year I would just kind of drop back and look for one guy and if he wasn't open, I just would kind of make something happen. This year I know there's a second or third option."
As one source in Pittsburgh's front office said this week, "Their secondary is not very good."
That would lead many to believe the Steelers will attack down the field.
"The defense has got to go out and do their job despite the adversity we run into," said safety Terrence Kiel.
"The front seven is taking it personal to get as much pressure on the guy as we can to get him uncomfortable," linebacker Steve Foley added.
But even then, it will take a colossal effort from the Chargers defense to keep containment. The secondary can't afford to have lapses in coverage as Roethlisberger buys time with his feet.
Otherwise, it could be a long day for San Diego on their home turf.