If Lito Sheppard were a quarterback instead of a cornerback, this might be more of an issue. If he played the premier position in football, you might say that he is injury-prone, not durable, or unable to push through the rigors of a 16-game season.

You might notice that he has not made it through an entire season since 2004, or you might keep closer track of the injuries that have sidelined him year after year. The high ankle sprain in 2005 that ended Sheppard's season in mid-November. The ankle injury early in 2006 that cost him three games. The shoulder injury that kept him out of a playoff game against New Orleans. The knee sprain that has dogged him this season.

Everyone wants to speculate about what's going to happen to the $100 million quarterback this off-season. But what about what's going to happen to Sheppard? And to Sean Considine? And to Brian Dawkins?

When compared to the secondary, there are no issues at quarterback.

Sheppard is a Pro Bowl player when healthy. Even missing games early last season, he made it to Honolulu for the second time in his six seasons in the league. He is fast and tough, good in coverage, and instinctive with the football. But Sheppard's injuries are mounting quicker than a kid's Christmas wish list, and the training room is getting awfully crowded.

We won't know until today whether Sheppard merely tweaked his sprained knee ligament Sunday against Seattle, or whether he is going to need to take another month-long hiatus to get it right. Clearly, against the Seahawks Sheppard was trying to push through the injury, but it appeared that he couldn't keep up with the receivers he was charged with defending.

Sheldon Brown said he was trying to help Sheppard on the one play on which Brown got burned for a touchdown. Shortly thereafter, the coaches pulled Sheppard out of the game. He watched the last quarter and a half from the bench, with a big parka pulled around his shoulders.

Afterward, as his dress clothes hung in his stall, Sheppard was nowhere to be found in the locker room - presumably getting treatment on his knee. Andy Reid hasn't said yet exactly what the latest problem is, other than Sheppard had "knee inflammation" and was "day-to-day", which in the don't-divulge-anything coachspeak prevalent these days could mean "week-to-week" or "for how long I don't know."

That could be a big problem for the Eagles as they make one last attempt to make a run at this season. Thanks to an inability to muster any momentum, the 5-7 team has zero margin for error. It's essentially win or go home.

The Eagles' pass defense, thought to be a strength coming into the season when compared to the run defense, has been mediocre at best. It ranks 19th in the league, allowing 220.5 passing yards per game, and has given up 15 touchdowns. That's not the 24 passing touchdowns Cincinnati's defense has give up, but it's not the seven Seattle's defense has allowed, either.

The Birds' run defense, by comparison, ranks ninth in the league, allowing just 96.8 yards per game and just eighth rushing touchdowns.

Clearly, all of the secondary's problems do not fall on Sheppard's slight shoulders. Considine never was the right fit at strong safety. Dawkins missed five games in the first half of the season with a tricky neck stinger. Quintin Mikell filled in ably for Dawkins and then Considine, whose season ended after he sprained a shoulder against Dallas, but he has his own sprained knee ligament that, like Sheppard's, is causing him to miss extended time.

And the Eagles misfired on Will James and Joselio Hanson. The coaches thought James, the former Giant, would push Brown for his starting spot. That never happened, and he has since been passed by Hanson, an undrafted rookie free agent out of Texas Tech in 2003 who, after a short stint with San Francisco, signed with the Eagles last season.

Every time Sheppard has to come out, the alternative is a steep decline in talent and reliability. And this just in: You-know-who on the schedule in two weeks has a pretty potent passing game with a pretty dangerous receiver who just loves to punish the Eagles.

Regardless of what happens with this season, the Eagles are going to have some big decisions to make with regard to their secondary. They'll need to take a serious look at the safeties. Dawkins isn't going to play forever. Mikell is a terrific option, but what about Considine, or J.R. Reed, or perhaps a free agent?

With Sheppard's injury history, they'll need a viable backup corner, a third starter, if you will, like when they had Rod Hood.

A healthy Sheppard is by far the best option, but we haven't seen a healthy Sheppard for a while. Think the Eagles have noticed?

Contact columnist Ashley Fox at 215-854-5064 or afox@phillynews.com.