Best way to tell teams on the rise is QB stats

Defenses might win championships, but not without a top-level quarterback.

For the past several years, the quarterback completion percentage has been a figure I've been clinging to in evaluating teams. In looking for potential sleeper teams or teams that could improve into championship contenders, I start with the quarterback who can improve the franchise's completion percentage.

Arguably, completion percentage is a weak evaluating number. Stats wizards would tell you yards per attempt is a more valid number, but that's a harder concept to embrace. Yards per attempt might show a team's ability to stretch the field, but it doesn't capture the efficiency of a quarterback. Old coaches say when you pass, three things happen and two of them -- incompletions or interceptions -- are bad, but the feel of a 60 percent passer is much easier to understand than that of a 6.78 yards-per-attempt thrower.

After looking blindly at quarterback numbers for years, I broke down a few statistical trends to get a better grasp of the quarterback numbers. Simply put, I put together a four-year database that included records, strength of schedule, offensive yardage and rankings, completion percentage, yards per attempt, and average points per game.

Guess what? I found something. My instincts were right. Although this isn't an exact science, a quarterback who can improve his completion percentage by four points and maintain a respectable yards per attempt in the mid-6 range could propel his team into a playoffs.

Going into last season, the easiest predictions came in the AFC. The addition of Steve McNair in Baltimore and the transition from Drew Brees to Philip Rivers in San Diego, coupled with an easier Chargers schedule, would produce two playoff teams.

McNair completed 63 percent of his passes, an improvement on Kyle Boller's 58.4 percentage of the previous year. Scoring went from 16.6 to 22.1 points a game, and McNair had a solid 6.52 yards per attempt. Helped by a relatively easy schedule, the Ravens went from 6-10 to 13-3. That was predictable.

Rivers had a tough act following Brees, but his teammates knew he had the skills. Rivers is taller and has a stronger arm than Brees. He's also every bit as smart and mentally tough as Brees and, after two years of sitting, Rivers wasn't going to be a failure. Rivers completed 61.7 percent of his passes, which was lower than Brees' 64.6 percent, but he bettered Brees' yards per attempt average (7.15) with a 7.37. Scoring jumped from 26.1 to 30.8 and, buoyed by an easier schedule than 2005, the Chargers went from 9-7 to 14-2. Also predictable.

The trickier prediction involved Brees, who signed with the Saints. Brees was coming off major shoulder surgery, so his health couldn't be guaranteed. But if you believed Brees' medical reports, the Saints were a playoff pick.

Brees was a savior in New Orleans, completing 64.3 percent of his passes, an 8.6 percentage point improvement over Aaron Brooks. His yards per attempt is what jumps out at you, though, as he vaulted past Brooks' 6.69 to 7.98. The Saints went from 3-13 to 10-6, and scoring jumped from 14.7 to 25.8.

Over the past four years, the numbers tell a good tale. An improvement of 4 percentage points in completion percentage -- coupled with good yards-per-attempt numbers -- can be worth a four-point improvement in team scoring. That translates into about a point a game per percentage point.

To explain what that means will cause me to be a little geeky. I tried to use one of the sabermetric formulas to equate the value of a four-point offensive improvement. In baseball, runs are everything. Evaluators can do a pretty good job of figuring out the success rate of a team over 162 games by using those old Bill James formulas involving runs scored and runs allowed.

So, putting up four more points a game -- 64 points a season -- equates to a 1.4-win improvement.

Enough about the stats. Let's look ahead to putting into perspective what might happen in 2007. Let's play the percentages.

The Bengals, Seahawks, Cardinals, Steelers, 49ers and Panthers are prime candidates for making completion percentage jumps of 4 percentage points. Of those six teams, only the Seahawks made the playoffs.

The Cardinals and 49ers are trendy playoff picks this year for good reason. Both teams have talented young quarterbacks who are ready to blossom. Alex Smith of the 49ers went from a 50.9 percent thrower to 58.1 last year. That helped improve the scoring from 14.9 to 18.6, and the 49ers improved three games to 7-9. Although Smith's yards per attempt were meager at 6.54, that was up from 5.30 and should improve even more this season with Vernon Davis having a year under his belt and Ashley Lelie and Darrell Jackson added to the receiving corps.

Smith should turn into a 60-plus percent throwers, as should Matt Leinart of the Cardinals. Leinart completed 56.8 percent of his passes as a rookie, which is exceptional. Rookies normally complete 53.3 percent of his passes. If Leinart can get his percentage into the 60s, Arizona scoring should vault into the 20s and the Cardinals should be an eight- or nine-win team.

The Seahawks and Panthers were wounded offenses last season. Matt Hasselbeck missed games with a bad knee and was playing with a bad left shoulder. His completion percentage dropped from 65.5 to 56.6, and Seattle's scoring fell from 28.3 to 20.9. Hasselbeck should be back throwing in the 60 percent range.

Jake Delhomme had a horrible year. Although he completed 61 percent of his passes, his yards per attempt dropped more than a yard per throw to 6.51. The Panthers went from a 24.4 scoring average to 16.9. If Delhomme struggles again, Carolina could go to David Carr at midseason, but it's reasonable to expect the Panthers offense to rebound.

The most exciting study is Carson Palmer. Palmer might be the third-best quarterback in football, behind Peyton Manning and Tom Brady. He came off a knee reconstruction and completed 62.3 percent of his passes for an offense that scored 23.3 points a game. In 2005, Palmer completed 67.8 and the Bengals averaged 26.3 points a game.

Now that he can work every day on fundamentals, Palmer set the goal of completing 70 percent of his passes out of the no-huddle offense. If he does, that should make the Bengals a double-digit winner -- as long as their defense doesn't regress.

Naturally, the Bengals will have to watch Ben Roethlisberger in Pittsburgh. Roethlisberger is a career 62 percent thrower, but more will be asked of him this year. The Steelers should put up between 22 and 25 points a game. After a 59.7 percent season, Roethlisberger should bounce back.

Watch those six teams for major offensive improvement this season.

John Clayton is a senior writer for ESPN.com.