Bart Starr, the greatest big game quarterback of them all, is coming out of semi-retirement on February 5 to toss the coin for Super Bowl XL at Detroit’s Ford Field. After the game, he’ll be presenting the Lombardi Trophy to the winner. As always, Starr’s timing is perfect – this year he’ll be shaking hands in the postgame locker room with the current quarterback whose style most resembles his: the Steelers’ Ben Roethlisberger.

For the second consecutive week, playing on the road against a higher seeded team, Roethlisberger came out firing and knocked a home team back on its heels, then used a precise, controlled possession game to eat the clock. He has now stunned the defensive units of the Indianapolis Colts and Denver Broncos in front of their hometown fans. The Seattle Seahawks, whom the Steelers will face in Detroit a week from Sunday, will have nothing new to show him.

Get on the bandwagon now and avoid the rush: Roethlisberger is the best quarterback in the game today – not as great a passer as Peyton Manning or Tom Brady, perhaps (just as Starr did not throw quite as well as Johnny Unitas or Sonny Jurgenson), but a better quarterback – a better reader of defenses, a better playmaker, a better leader. And at age 23, he is on the verge of becoming the youngest legend in NFL history.

Changing plays at the line of scrimmage with abandon and picking up the Broncos’ blitzers as if they had flares on their helmets, Roethlisberger picked the Denver defense – which was tied for second in the AFC in fewest points per game – to pieces. Seven of the Steelers’ first 11 snaps were passes, five of them completions. That was just their warm-up. Leading 3-0 early in the second quarter, Roethlisberger took his offense 157 yards on 23 plays on three consecutive possessions. In the process, he chewed up 12 of the quarter’s 15 minutes. And he did it with style, connecting on seven consecutive second- or third-down passes and hitting six different receivers. The Steelers’ receivers don’t need to be introduced before the Super Bowl; Roethlisberger let them take their bows, one at a time, while humiliating the Broncos’ defense in the second quarter.

Like Starr in his classic postseason wins, Roethlisberger’s plain statistics don’t tell the full story. He completed 21 of 29 passes for 275 yards and two touchdowns – both in the second quarter – but he was much better than that. Sixteen times he threw on third down needing an average of seven yards to convert, hitting on 10 for 181 yards. On second down he was four of six for 56 more.

Clutch performance may be difficult to identify in baseball and basketball, but in football it’s fairly easy: A great quarterback is expected to step up in big games and to be able to hit on third down passes. Roethlisberger’s ability to do this, to keep opposing defenses off balance with his play calling, to read defenses and adjust, and to spot the open receiver is uncanny. He is now 4-1 in the postseason and headed for his first championship game, a ways to go before he can equal Starr’s postseason record of 9-1 and five championships or Tom Brady’s 10-1 and three titles, but he’s getting there quickly.

Terry Bradshaw, who won four Super Bowl rings with the Steelers, did not appear in his first playoff game until he was a year older than Roethlisberger and did not play in his first Super Bowl till he was three years older. Joe Montana was two years older than Roethlisberger when he first played in the postseason. Brady, like Roethlisberger, led his team to the Super Bowl in his second season, but he was a year older then than Roethlisberger is now. None of them was as good as early as the Steelers’ young field general. Neither Bradshaw nor Brady ever averaged his 8.9 yards per throw in a season; Montana did it once, in 1989, when he was 33. Roethlisberger’s average for his first two seasons in the NFL is 8.9. In the playoffs, he’s averaging slightly better than 8.6.

The Steelers are one of those teams that looks like they have a better running game than they really have because they get so many chances to run the ball. The reason they get so many chances is because Roethlisberger completes so many second- and third-down passes, giving them whole new sets of downs with which to demoralize and physically punish opposing defenses with their massive offensive line.

Yesterday, the Steelers could scarcely run the ball at all, just 90 yards on 33 tries, a dismal average of 2.7 yards per try. They had only one gain longer than seven yards, a run by Willie Parker for 14. Take away Parker’s run and the Steelers averaged a ridiculously low 2.4 yards a try – that wouldn’t give you a first down if you did it four times. The Broncos actually ran the ball fairly well against the Steelers, with 97 yards on 21 carries for a 4.6 average – very nearly what they averaged during the season.

It mattered not at all. Once the Steelers jumped to their big lead, the Broncos were reluctant to keep the ball on the ground for fear of running the clock out on themselves. What mattered was that Roethlisberger outpassed Broncos quarterback Jake Plummer (18 of 30 for 223 yards, one touchdown and two interceptions) just as he outpassed Peyton Manning last week in Indianapolis.

Next week, Roethlisberger will finally meet a quarterback who is better than he is. Unfortunately for the Seahawks, his name won’t be Matt Hasselbeck. It will be Bart Starr.

Mr. Barra is the author, most recently, of “The Last Coach: A Life of Paul ‘Bear’ Bryant.”