By Tim Graham
If not for Buffalo Bills cornerback Terrence McGee's wonky knee, Aaron Williams might already have been supplanted in the starting lineup.
McGee missed a second straight practice today to rest his knee. He played 48 percent of the defensive snaps in Sunday's victory over the Arizona Cardinals -- up from 22 percent a week earlier -- and is being given time to recoup.
That's the most action McGee has seen this year, but that doesn't necessarily mean his reps are increasing because he's taking over Williams' job opposite rookie Stephon Gilmore.
McGee admitted his knee -- not performance -- still is dictating how much he plays. He tore his patellar tendon last season and continues to experience discomfort.
"The majority of the time I can feel it," McGee said. "It hasn't been real disappointing because I'm able to go out there and cover guys, but you want to get to that point to where you're not worrying or thinking about your knee. I'm trying to get to that.
"I've had times in practice where the whole week it felt good. Then you get to the next week in practice and it feels like I just had surgery. Hopefully I start stacking [practices] where it's consistent week to week."
McGee remarked that he enjoyed a couple series in Arizona when he totally forgot about his knee injury.
McGee, in a rotation with Williams, was on the field for 35 plays. He saw only 15 plays against the San Francisco 49ers in Week Five.
Williams got 41 plays (56 percent) on Sunday and 47 plays (70 percent) in San Francisco.
For a comparison, Gilmore played 96 percent of the snaps in each of the past two games.
Bills coach Chan Gailey said the Williams-McGee rotation will continue but that Leodis McKelvin and Justin Rogers could enter the equation if the position doesn't find stability.
"We'll just see how that unfolds," Gailey said. "Then if that doesn't work, we'll look at who's next up."
Williams sometimes looks lost in coverage. Of all cornerbacks who've played at least 25 percent of their team's defensive snaps, the analysts at ProFootballFocus.com rank Williams 90th.
PFF, which tracks each play, says no cornerback has given up more than Williams' five touchdown catches, and 60.9 percent of passes thrown into his coverage have been completed. Opposing quarterbacks have a 129.2 passer rating when throwing at receivers guarded by Williams.
"It's just like any other position on the field," Gailey said of last year's 34th overall draft choice. "Once you do a couple things then you gain confidence in it. He just needs to keep playing and keep getting confidence in himself.
"He's got ability. We all have seen that. And I think he's going to be just fine. That's not one of the biggest problems that we have. If it becomes a bigger problem, then we've got to make an adjustment."
PFF ranks Gilmore 63rd among all cornerbacks. He has given up three touchdown throws, 55.6 completions into his coverage and a 115.6 passer rating.
McGee is 82nd, albeit on limited plays. He hasn't given up any touchdowns, but opposing quarterbacks are completing 68.8 percent of their throws into this coverage and have a 99.7 rating.
McGee acknowledged that if he wasn't dealing with his knee problems that he would be in better position to take over the starting role.
"If everything was OK, that's what I would want," McGee said. "If I'm feeling 100 percent, I feel like I would compete for that job a little bit more.
"Last week was probably one of the times where I felt I was moving better. I saw a difference last week. But as a corner, overall, you want the big plays, the interceptions. I'm still looking forward to making a bigger impact."
(Photos: John Hickey and James P. McCoy/Buffalo News)