ORCHARD PARK, N.Y. - Mario Williams suggests the Buffalo Bills' personnel doesn't fit coach Rex Ryan's defensive scheme, insisting he's simply stating a fact and not intending to be critical.

As for whether he is the right fit, the Bills' top pass-rusher referred to how Buffalo's defence has failed to play to its high-priced expectations this season.

"A scheme's a scheme, but to say that it's going to produce, we haven't had the numbers," Williams said Wednesday. "There's nobody saying anything that what (Ryan's) doing is wrong. But for what's out there, the personnel might not be the right personnel."

The underperforming defence and Williams' role in it have been a season-long issue, a key reason why Buffalo (6-8) has been eliminated from playoff contention as it prepares to host Dallas (4-10) on Sunday.

Buffalo ranks 21st in yards allowed and 30th with 20 sacks.

That's hardly what anyone expected from a unit that returned mostly intact a year after finishing fourth in the NFL in yards allowed and had a league-leading 54 sacks. It's an even a bigger disappointment to happen under Ryan, the first-year coach with a respected track record as a defensive specialist.

Williams' numbers are down. A year after he had a career-best 14-1/2 sacks, he's managed just four.

The issue for Williams is Ryan's system relies more on linebackers and safeties than linemen.

"What we're doing as a defence just has not worked for us this year," Williams said. "Now I'm not saying about the scheme (like), 'Throw it out. It's garbage or whatever.' No. I'm just saying what is what. That's it."

Williams spoke for 15 minutes at his locker in front of a large group of reporters. The crowd eventually included linebacker Manny Lawson and safety Aaron Williams, who craned their necks to hear.

Lawson eventually told Mario Williams to stop talking because it was time for them to work out.

This isn't the first time Williams has shared his opinions on what's gone wrong this season. In October, he questioned why he was being asked to drop back in coverage, something he's never done in his previous nine seasons. Following a 35-25 loss at Washington on Sunday, Williams wondered why the Bills were changing players even with the opposing offence breaking the huddle.

Williams took issue with anyone who would accuse him of being critical.

"How's that a complaint when you ask me a question and I answer it?" Williams said. "So maybe I just shouldn't say anything."

The trouble is, some teammates interpreted Williams' comments as suggesting there might be a division in the locker room or a rift between players and coaches.

"To win in this league, you've got to be all together on effort, scheme, everything, and I don't think we were, going into last game based upon the postgame comments," centre Eric Wood said, referring to Williams.

Without referencing anyone specifically, linebacker Preston Brown said it was time to stop pointing fingers.

"We can't go around saying it's the scheme or everybody's not playing with effort. I think it's just mentally everybody wasn't there," Brown said.

He then added that "everybody has been kind of doing their own agenda on our side of the ball."

Ryan had no problem with Williams' comments, and reiterated that he has no intention of muzzling players.

"I'd rather give our fans and everybody a true picture of this team," Ryan said. "I've never been afraid of that in my life."

Ryan said Williams spoke out of frustration, and believes the player does fit his system.

And yet, without getting into specifics, Ryan has already indicated that "drastic changes" might be in order this off-season.

Williams' future in Buffalo was uncertain even before his production started tailing off. He has two years left on the $100-million contract he signed in 2012, due to make a $12.1 million base salary next season. That's an expensive proposition for Buffalo given Williams' drop in production and with the Bills already having little room under the salary cap to add and re-sign players.

Williams understands his days in Buffalo might be numbered.

"Of course there'll be changes," Williams said. "I mean, that's obvious. You just wait and see if my number's called."

NOTES: RB LeSean McCoy (right knee) did not practice and Ryan said it might be unrealistic for him to play Sunday. ... Ryan said Wood, QB Tyrod Taylor, LG Richie Incognito and DT Marcell Dareus were made Pro Bowl alternates. ... TE Charles Clay (back) returned to practice after missing one game.

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