On the surface, Friday night's preseason win over the Minnesota Vikings looked like an impressive showing by the Buffalo Bills defense.

After all, they held the Vikings to just three points through the first three quarters. The Bills had four sacks, forced a fumble, and limited Minnesota to just 41 first-half rushing yards. They even added a touchdown on a fumble recovery.

This part is true: the Bills defense kept the Vikings on their heels, especially early in the game. Never did Christian Ponder or Matt Cassel look comfortable under center.

But before anyone gets carried away with the success of defensive coordinator Mike Pettine's pressure schemes, let's remember one thing: Ponder and Cassel were two of the NFL's worst quarterbacks last season.

The Vikings held their best player, running back Adrian Peterson, out of action on Friday night, but beyond that, Minnesota did not seem to anticipate the aggression of the Bills defense in the teams' second preseason contest.

"Everybody has their way of approaching the preseason, and that’s their choice," Vikings coach Leslie Frazier said after the game. "They did some good things. It’s preseason. They have the option to do whatever they want to do. We didn’t spend a lot of time preparing to play Buffalo."

"Just their whole defense was pretty exotic. They had some exotic personnel and different schemes, it was a little different and sometimes it was a little hard for us to identify," Ponder added.

Was the Vikings not being ready for Pettine's defense the Bills' problem? Not at all. And come the regular season, when teams do prepare for it, Pettine still has ways of keeping defenses off balance.

After the New York Jets were routed 45-3 by the New England Patriots in Dec. 2010, the Pettine-coached Jets defense turned to a coverage-heavy, extra defensive back- scheme in the teams' ensuing playoff game. Patriots quarterback Tom Brady, expecting blitzes and pressure looks, was stymied, and the Patriots fell to the Jets, 28-21.

It's that unpredictable element that the Bills hope Pettine will bring to the defensive philosophy this season. It won't always be about pressure and sacks.

But for right now, the performance of the Bills defense on Friday night shouldn't be made into anything more than a step in the right direction. It was encouraging, but not excellent.