The late Don Smith never claimed his passer-rating formula was perfect.

Quite the opposite, in fact.

According to an outline for the rating system, Tom Brady would fall in the "top tier" category. Al Bello/Getty Images

"Some people call it a quarterback rating system, but that really is not what it is," Smith told me during a 2002 interview. "It’s simply a passing statistic."

I've actually defended Smith's rating system because the quarterbacks with the highest ratings -- Tom Brady, Philip Rivers and Aaron Rodgers led the way last season -- usually are the best quarterbacks. But there's so much more to quarterbacking than passing stats for touchdowns, interceptions, attempts, completions and yardage.

Game situations should count for something, and now they do.

With input from football people, including ESPN analyst Trent Dilfer, our statistical analysts have developed a 100-point ratings scale for quarterbacks taking into account advanced stats, game situations and relevant non-passing stats, including fumbles and sacks, to evaluate quarterbacks far more thoroughly. The methodology is complex -- one of the formula's key algorithms spans some 10,000 lines -- but the resulting "Total Quarterback Rating" (QBR for short) beats the old passer rating in every conceivable fashion. The ratings scale will debut this season.

I've been bugging the Stats & Information team for a sneak peak ever since learning former NBA statistical analyst Dean Oliver had joined our production analytics unit and was playing a prominent role in QBR development. Oliver, a Caltech grad with a Ph.D. in statistical applications, revolutionized how NBA teams use advanced statistics. Menlo College professor Ben Alamar, who has consulted with the San Francisco 49ers, is also part of the team.

Our stats team has been using game video to track stats relating to pressure, personnel, formation, game situation and more since 2008. The QBR stat represents a significant leap in harnessing those statistics for something more.

The old formula Smith created treated stats the same regardless of circumstance. A touchdown pass thrown against a prevent defense during a blowout defeat equals one thrown against pressure to win the game. A 5-yard completion on third-and-4 counts the same as a 5-yarder on third-and-15. A critical quarterback scramble, sack or fumble doesn't even factor.

"There is no way to statistically say how effective a guy is under fire," Smith lamented during our 2002 conversation. "None of that can be put into something like this."

Now it can, along with a whole lot more.

The QBR formula takes into account down, distance, field position, time remaining, rushing, passing sacks, fumbles, interceptions, how far each pass travels in the air, from where on the field the ball was thrown, yards after the catch, dropped balls, defensed balls, whether the quarterback was hit, whether he threw away the ball to avoid a sack, whether the pass was thrown accurately, etc. Each play carries "clutch weight" based on its importance to game outcome, as determined by analyzing those 60,000 plays since 2008. The stats adjust for quarterbacks facing an unusually high number of these situations.

"If it is a running clock late in the game, maybe you only get a few yards here or there, that is the right football play to make," Jeff Bennett, senior director of ESPN's production analytics team, said Sunday. "We spent a month learning about ratings to make sure quarterbacks couldn’t game the system, so they're not afraid to throw that deep pass at the end of the first half and risk an interception."

I've seen an outline for the rating system breaking down 2010 quarterbacks into six general categories, from top tier to poor. Precise rating numbers were not yet available. The quarterbacks under consideration broke down as follows:

ESPN plans to enlist several quarterbacks when introducing the stat during an hour-long "SportsCenter" special Friday at 8 p.m. ET. We'll be referencing the stat on the blogs and elsewhere. Bennett said he's allocating enough manpower to produce ratings on game days, a huge help for those of us analyzing player performances shortly after games.

"We want to reward a good football play," Bennett said.