FOXBORO -- Times are tough for the Bills' defense.

It has gone from the top of the NFL at the end of last season to 31st after seven games this year.

On Oct. 2, Buffalo lost to the Saints. That's hard to do. On Oct. 9, Miami quarterback Gus Frerotte went 21-for-33 against the Bills' once-solid secondary. On Oct. 16, the Jets' Curtis Martin ran for 148 yards against the once-stalwart run defense. And on Oct. 23, the Raiders' Lamont Jordan ran for three touchdowns and 122 yards.

On Sunday, the Patriots come back from their bye week and play the Bills at Gillette Stadium. Even Buffalo knows the Pats' offense needs bibs as it eyes the Bills' defense hungrily.

"In the National Football League, unless you make your corrections from the previous week, you will get big doses of that to see if you've made those corrections," said Bills free safety Troy Vincent. "We've struggled since Week One in the running game. We've given up big plays periodically in each of those football games. Until we make those corrections, we'll see that every week. They've had an additional week to break us down and an additional week for Corey (Dillon) to get back on his feet. He's a fine football player, one of the best backs in the league and a Pro Bowler a year ago."

Which is precisely the way the Patriots would like them to feel by 11 p.m. Sunday night as the fourth quarter begins.

Other than the day in Atlanta when Dillon ran for 106 yards, New England's running game has sputtered all year. New personnel on their side and tough personnel on the opposing side have seemed to be the primary reasons for that. But if New England can't execute a successful land grab against a Bills team that's allowing an average of 159 yards per game to its opponents, perhaps the problems are more complex.

There are reasons, of course, for the Bills' defensive nosedive. And they are similar to the reasons New England's defense has become so porous this year -- injuries. Buffalo lost its terrific outside linebacker, Takeo Spikes, and defensive lineman Pat Williams. Then Williams' replacement, Ron Edwards, went down.

Throw in the fact that ex-Pat Lawyer Milloy has been dinged up, and you have down-the-middle-of-the-defense reasons for the fall-off.

"You are going to miss something when you lose those guys," Bills head coach Mike Mularkey said when asked about the losses his defense has suffered. "But good football teams -- and we are playing one this weekend -- find a way to fill that spot and make up for it. . ."

The Patriots -- as they have a habit of doing -- don't look at the Bills as limping. They've just been a victim of circumstance, it seems.

"There's been a few things that skewed the numbers," Patriots head coach Bill Belichick said when asked why the opposition's rushing numbers are so high. "Curtis (Martin) had a couple of long runs, but there's been a bunch of runs where guys didn't get back to the line of scrimmage."

Well, the same thing has happened to the Patriots' defense, but Belichick would never be so diplomatic with his guys. Truth is, Buffalo is reeling and needs to do something to get right. But what?

"We have not been a good tackling team up front," said Vincent, a pleasant guy who probably will get away with selling his teammates down the river so boldly. "We're a gap-control football team and we just have to get men taking care of their own responsibilities. When things aren't going well and the momentum's not on our side of the field, we have a tendency to try to do things that we shouldn't be doing, and you're not taking care of your own responsibilities.

"(Forget) the injuries. When guys come in, they have to step up and they have to play. We just haven't been a good tackling team (or) a good, sound team at times during football games. Sometimes we've been awfully good, then at other times we haven't been good at all."