Up is down and down is up this year in the AFC West, home to one of this year’s most disappointing teams and one of the biggest surprises. The Kansas City Chiefs, coming off a 13-3 season in which they won their first nine games, are 1-4 with every possible break going against them. On the other hand, you have the San Diego Chargers, who won only four games last season and were expected to be even worse this year. Instead, they are 3-3 and would have already matched their win total from 2003 if not for the fourth quarter heroics of Falcons quarterback Michael Vick on Sunday.

The Chiefs and Chargers are not only linked because they share a division, but also because, when it comes to each team’s changing fortunes, one mirrors the other. The decline of Kansas City and rise of San Diego demonstrate the importance – and unpredictability – of special teams.

Football writers often make vague reference to the importance of special teams, but only field goal kickers ever really get much attention. Last year was an exception, as Kansas City returner Dante Hall became a media darling. (How often does a kick return specialist show up on “Late Night” with David Letterman?) Hall returned a punt or kick for a touchdown in four straight games early in the season, and by midseason the talk was less about how to stop Priest Holmes and more about how to kick the ball away from Hall.

Spurred in part by Hall’s success, I developed a metric at my Web site,FootballOutsiders.com, to measure the value of special teams. In general, each yard on the field has a value based on whether the offense or defense is likely to score the next points, and how many points they are likely to score. The value of each yard goes up gradually from -2 points on your own goal line – the value of a safety – to 7 points on your opponent’s goal line, the value of a touchdown. Kicks, punts, and returns are judged by how much field position value they gain for the return team compared to the league average on kicks from the same line of scrimmage. Each number is adjusted to account for specific weather conditions and altitude. Field goal kicking is compared to the league average from each specific distance.

According to this measure, the field position that Kansas City gained from kick and punt returns in 2003 – including Hall’s four touchdowns – was worth 27.1 points compared to returns for an average team. Hall was far and away the most valuable return man in the league; only Jerry Azumah of Chicago was even close. In total, the Kansas City special teams – including kicker Morten Andersen, punter Jason Baker, return coverage, and other returns along with those by Hall-were worth 31.5 points over an average team, second in the league behind Baltimore.

What a difference a year makes. Before the season the Chiefs waived Andersen and Baker and replaced them with two rookies, kicker Lawrence Tynes and punter Steve Cheek. The result has not been pretty. This week saw perhaps the most emotionally damaging loss of the year, a 22-16 defeat in Jacksonville where Tynes missed a field goal and an extra point in the fourth quarter. But Kansas City special teams were a problem long before Tynes hit the right upright with his extra point attempt on Sunday.

Overall, including punts, kicks, and returns, Kansas City’s special teams have been 14.7 points worse than average, last in the NFL this season. Even Hall has been subpar; his average on kick returns has dropped from 25.9 yards to 20.9 yards, while his average on punt returns, including fair catches, has dropped from 16.3 yards to 10.3 yards.

Meanwhile, San Diego’s special teams have undergone the opposite turnaround. Last season, special teams cost the Chargers 17.3 points compared to the average NFL team, which ranked them 27th in the NFL. Particularly atrocious were Steve Christie’s kickoffs, which cost the Chargers 14.3 points worth of field position. The entire season, Christie had not a single touchback – not even when the Chargers played in mile-high Denver.

When the Chargers selected Iowa kicker Nate Kaeding with their third round pick in the 2004 draft, it was seen by many observers as proof that the Chargers were the NFL’s worst-run franchise. But between the fine play of Kaeding and the kickoff returner Tim Dwight’s comeback from an injury-riddled 2003 campaign, the San Diego special teams rank fourth in value this season. Kaeding has been perfect on field goals, including two over 50 yards, and good on kickoffs as well.

The special teams switch between San Diego and Kansas City is actually not very surprising. In general, special teams performance is far less consistent from year to year than offense or defense. Of the 18 teams that received positive value from their special teams in 2003, 10 have received negative value so far this season.

There are plenty of reasons for this. Special teams get far fewer opportunities to make a mark, so a few big plays can skew a team’s statistics. Special teams also undergo heavy personnel changes between seasons. Lower-round rookies have to prove themselves on coverage teams, replacing more expensive veterans who get cut.

Return men often graduate into the starting lineup as defensive backs or wide receivers, with rookies taking their place. Second-tier free agents who fill slots on special teams move from city to city every year or two. So do many kickers and punters.

Baltimore is a major exception – the Ravens led the league in special teams value in 2003 and lead again in 2004. This is partly because they carry separate kickoff and field goal kickers who have both been great, and partly because the performance of rookie return man B.J. Sams makes up for an off-year from 2003’s top-rated punter, Dave Zastudil.

The good news for the Chiefs is that some of their problems can be fixed. They waived Cheek and brought back last year’s punter, Baker, and you can’t expect Tynes to miss extra points very often.

The bad news for Kansas City – and good news for San Diego – is that special teams are much more consistent from the beginning of the season to the end of the season than they are from year to year. Special teams will probably be helping the Chargers win games, and the Chiefs lose them, for the rest of 2004.

Mr.Schatz is the editor in chief of FootballOutsiders.com.