It’s well known among NFL fans that the last five teams to lose the Super Bowl have not even made the playoffs the following year. When Seattle began the year with three straight wins, it looked as if the Seahawks might break this infamous curse.

But in the past few weeks, things have turned sour for the Seahawks. Seattle lost reigning MVP Shaun Alexander to a broken foot and was dominated in losses to both Chicago and Minnesota. To add injury to insult, the Seahawks lost quarterback Matt Hasselbeck on Sunday, thanks to a hit below the knees by Minnesota linebacker E. J. Henderson. The initial fears of a torn ACL that would knock the quarterback out for the season proved to be unfounded, but Hasselbeck still will miss at least three weeks, and probably more, with a torn MCL in his right knee.

Hasselbeck’s injury is the just the latest of many to hit the Seattle offense this year. Most of the attention has been on the injury to Alexander, which was almost inevitable given the running back’s workload last season. Alexander’s 430 carries in the regular season and postseason last year ranked as the sixth highest total in NFL history.

In past years, however, Alexander’s backup, Maurice Morris, has always played extremely well. This year, he’s struggling, just like Alexander did before he broke hid foot — mainly because of injuries on the Seattle offensive line. The free-agent departure of Pro Bowl left guard Steve Hutchinson left a big hole, but that hole got bigger when the player who was supposed to fill it, veteran Pork Chop Womack, went down. Womack strained a hamstring in the preseason, then hurt his left knee and missed four games. The replacement for the replacement is Chris Spencer, drafted last year to be Seattle’s center of the future, but now stuck getting on-the-job training at a new position.

Other linemen have played hurt instead of missing time, but those injuries still have an impact. Left tackle Walter Jones hurt his ankle in the opening game against Detroit, and with less mobility than usual, he’s already given up more sacks than he did all last year. Right guard Chris Gray is slowing down due to age (he’s 36) and a sprained knee.

The injury to Hasselbeck far surpasses these other injuries in importance. Hasselbeck doesn’t get as much attention as the other top quarterbacks in the league, due in part to his quiet nature and less-than-matinee idol looks. But he’s been the best quarterback in the NFC over the past four years. His ability to read defenses and adjust plays at the line makes him the perfect quarterback for Mike Holmgren’s classic West Coast offense filled with short timing routes.

The drop from Hasselbeck to backup Seneca Wallace is colossal, far bigger than the drop from Alexander to Morris. Wallace doesn’t just pale in comparison to Hasselbeck. Based on what he’s done in preseason performance and a few regular-season snaps, Wallace also pales in comparison to the backup quarterbacks who sit behind the other top quarterbacks in the NFL: Jim Sorgi of Indianapolis, Matt Cassel of New England, and especially Charlie Batch of Pittsburgh.

After two years on the bench, Wallace finally got on the field in 2005, and even started the meaningless last game of the season. Then he played the second half against Minnesota on Sunday after Hasselbeck was knocked out. His career regular season numbers are not impressive: only a 54% completion rate, barely six yards a pass attempt, three interceptions, four fumbles, and just one touchdown. His career passer rating is 54.4; compare that to Cassel (89.4), Sorgi (99.3), and Batch (78.7, but much higher since joining Pittsburgh in 2002).

While nobody expected Seattle’s offense to have so many problems and face so many injuries, it would have been tough for the Seahawks offense to play as well as it did last year. An improving young defense was supposed to pick up the slack, leaving a team that was equally good and even more balanced.

But the defense hasn’t really improved from last year. There are strong points, to be sure: Like last year, the Seahawks are near the top of the league in sacking opposing quarterbacks. But Seattle’s secondary is still giving up too many big pass plays to opposing receivers, and the front seven is often passive on running plays, allowing the other team’s blockers to get to the second level with consistency. The Seahawks also have problems stopping the run on third down and have yet to stop a runner from converting on third-and-1.

If there is any good news for Seattle fans, it is the schedule. Kansas City’s improved defense should cause Wallace fits, and division rival St. Louis should be able to outscore a Hasselbeck-free Seattle offense. But games against San Francisco and Oakland are still winnable, and Seattle will hopefully get Hasselbeck back before December games against Denver and San Diego.

But hopefully is not definitely. Teams often underestimate how long a player will miss with an injury, or they rush players back before they are ready, only to get subpar performance. If Seattle does not get Matt Hasselbeck back at 100% for the final month of the season, the streak of Super Bowl losers who miss the playoffs will stretch to six.

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