Has Mario Williams met Bills' expectations?

Good, but not good enough.

That seemed be the perception of defensive end Mario Williams in his first season after he signed a six-year, $100 million contract with the Buffalo Bills in March 2012.

Dealing with a wrist injury and off-the-field distractions, Williams finished with 10.5 sacks last season, impressive for most but not for a player considered to stand at the top of the NFL's heap of pass-rushers.

Then came training camp this past July, when Williams reported with a sore foot, leading to several missed practices and groans from some fans who felt like another disappointing season was on the horizon.

But then Williams got healthy, and in Week 2 he exploded for a 4.5-sack performance against Carolina. He's added 5.5 sacks in the five games since, including a game-changing strip-sack of Ryan Tannehill that led to a Bills victory over Miami on Sunday.

With 10 sacks on the season, Williams has the most of any player in Bills history through seven games, besting Bruce Smith's nine sacks in the first seven games in 1997. He's on pace for about 23 sacks this season, which would surpass Michael Strahan's NFL record of 22.5 sacks in 2001.

But the question still lingers: Are the Bills getting everything they expected out of Williams?

Much of that hinges on how a sack is valued. Some say it's a deceiving stat, sometimes the product of a player being in the right place at the right time or an offensive lineman blowing his assignment. Others argue that it's an effective measure of defensive pressure, a momentum-disrupting play that can instill fear in an opposing quarterback.

Whatever the case, Williams believes that a sack is more than just an individual accolade, explaining to reporters after the Bills' win Sunday that his sacks have been a full-team effort this season.

"Without the help of my teammates I couldn’t have done it," Williams reiterated Wednesday. "We came out [and] played ball, played off one another and got after it."

Asked whether Williams' success on the stat sheet this season can be attributed to his own talent or the arrival of defensive coordinator Mike Pettine, Bills coach Doug Marrone joked that the answer would depend on whom you asked.

"I’m sure Mike would tell you it’s scheme and Mario would tell you it’s talent," he said.

In fact, Williams credited Pettine for the pressure the defense has generated, which is considerable: The Bills rank second in the NFL in disrupting opposing quarterbacks' dropbacks this season.

"Being able to go out there and just mix it up, we are moving around, having fun and getting after it to play off one another," Williams said. "It is definitely a great feeling for myself, I’m sure everybody else would say the same thing. It’s just a great time."

Marrone noted that Pettine has shown a willingness to move Williams across the formation, which has kept offenses off guard.

"I think a little bit of us being able to have the ability to move him a little bit, that definitely helps. People have a plan, if you’re just all the time you’re that right defensive end to the quarterback's left, people can game-plan that. I think it’s a little bit difficult when you have a player that moves around a little bit," he said. "He’s an outstanding player, he really is. I think you could put him anywhere and he’ll be productive."

All that withstanding, there have been times this season when Williams hasn't shown up. He notched just one tackle and a half-sack against the Cincinnati Bengals and was quiet Sunday before his two-sack explosion in the fourth quarter.

So are the Bills getting what they need out of Williams? Does he need to perform more consistently? Or has he put to rest the criticism that followed him throughout last season?