Shortly after the 2012 NFL draft begins Thursday at 8 p.m., Stanford’s Andrew Luck is expected to walk across the stage at Radio City Music Hall in New York to shake hands with Commissioner Roger Goodell as the top overall selection by the Indianapolis Colts.

Robert Griffin III, the Heisman Trophy-winning quarterback from Baylor, will have his moment in the spotlight soon thereafter, when, barring the unforeseen, the Washington Redskins make him the second overall pick.

This NFL draft is about the quarterbacks in line to be chosen first and second, and the night almost certainly will begin with Luck and Griffin hailed as the next greats at the sport’s most important position, the centerpieces of their franchises for years to come.

The outcomes of past NFL drafts, however, show that events are unlikely to play out quite that way, that the immense promise of Luck and Griffin probably won’t be fulfilled by both men. Draft history indicates that for every Drew Bledsoe, Peyton Manning and Donovan McNabb among the group of quarterbacks selected first and second in the same NFL draft, there is a Rick Mirer, Ryan Leaf and Tim Couch.

“It’s not surprising,” former Colts general manager Chris Polian said recently, going over the list of quarterbacks previously taken first and second in the same year. “It’s basically around 50 percent, historically, no matter where you’re picking in the first round.”

Two quarterbacks have topped the draft charts only four times since the NFL and AFL combined their selection processes in 1967. On three of those occasions, one of the two quarterbacks failed to have the successful NFL career predicted for him.

That was the case with Couch, the Kentucky product taken by the Cleveland Browns with the top overall selection in the 1999 draft, before McNabb was picked second by the Philadelphia Eagles (and Akili Smith went third to the Cincinnati Bengals). It was certainly true of Leaf, the second pick by the San Diego Chargers in 1998 after Manning went first overall to the Colts. And the same thing happened to Mirer, the second choice in the 1993 draft after Bledsoe was selected first by the New England Patriots.

Only in 1971, when Jim Plunkett went first to the Patriots and Manning’s father, Archie, went second to the New Orleans Saints, did both quarterbacks have productive NFL careers. Another successful NFL quarterback-to-be, Dan Pastorini, was taken third by the Houston Oilers that year.

Several experts said they expect Luck and Griffin to break the trend.

“I think these two are going to turn out the way we expect,” said former NFL quarterback Warren Moon, a member of the Pro Football Hall of Fame. “Maybe with some of those guys in the past, there were a few flaws. I don’t see that with these two guys. They’re both highly talented physically. They’re both intelligent. They’ve both got engaging personalities. They’re leaders. They’ve both taken their programs to high levels, elevated their teams. Now they both have the chance to do the same thing again at this level.”

Said Polian: “They have the right personalities. They both have family stability. They have the right makeup and the right support systems. No one can predict injuries. No one can predict how their teams will be built around them. But you’re looking at two guys who are above everyone else.”

The Chargers’ selection of Leaf in 1998 is perhaps the most harrowing cautionary tale in draft history for teams searching for franchise quarterbacks with the top picks. Bobby Beathard, the former general manager of the Redskins and Chargers, knows it well. He picked Leaf for the Chargers.

“I’m responsible for that one,” Beathard said. “The thing that messed me up is that [former Colts executive] Bill Polian wouldn’t swap picks with me. I wanted Peyton. I knew Archie and Olivia. I knew I wanted Peyton if I could get the first pick. Even after the draft, Polian said he wasn’t sure which one to take, but I don’t know whether to believe him on that.”

Manning became the only four-time most valuable player in league history for the Colts. Leaf played only 25 NFL games. He now faces felony charges in Montana stemming from allegations of burglary and stealing prescription medication.

“I know when we worked both guys out, we did not think Leaf’s arm was significantly stronger than Peyton’s,” said Chris Polian, Bill Polian’s son, who formerly worked for his father with the Colts. “That was supposedly the knock on Peyton, that his arm wasn’t as strong as Leaf’s, and we didn’t find that to be the case. And not that we really knew anything about Leaf, not that this foreshadowed anything, but I think there were some areas where he did not measure up to Peyton.”

Griffin faced some scrutiny last week when the Milwaukee Journal Sentinel quoted an unnamed NFL scout saying that he has a selfish streak. Another anonymous scout told the paper that Griffin doesn’t have vision or a feel for the pocket. But for the most part, the pre-draft evaluation process has been relatively kind to Luck and Griffin.

“It’s been a little different this year because there really hasn’t been much of a backlash against either guy, where people start questioning one thing or another,” Polian said. “There hasn’t been a Ryan Leaf comparison kind of thing, like when people started asking whether Peyton’s arm was as strong as Leaf’s was. Even though these guys are [numbers] one and two, it hasn’t been a real comparative thing, or a thing where they’re being picked apart too much.”

Moon served as an adviser last year to Cam Newton, the quarterback drafted first overall by the Carolina Panthers who broke Peyton Manning’s NFL record for passing yards by a rookie last year. Moon called Newton’s rookie-year success “mind-boggling,” and said he expects any young quarterback to have ups and downs.

“They’ll both go through their rookie struggles,” he said. “They’ll have to learn. People might blitz them like crazy at some point and there will be weeks when they’ll handle it, and weeks when they won’t. I think they’ll both be excellent quarterbacks. But it’ll take some time.”

Despite the history of 1-2 quarterbacks, few seem to expect Luck or Griffin to go the way of Couch, Leaf and Mirer.

“I would say because of the intangibles that both of these guys have, because of the overwhelming success they had in college and brought to their programs, it’s hard to see them not living up to their potential,” Polian said. “Both of these guys elevated their programs. Each guy has their own skill set, but both are extremely talented.”