Key issues for three contenders

Eli Manning, who has been sacked six times in the past two games, has not played well of late. Jeff Zelevansky/Getty Images

With a month and a half to go in the 2012 NFL regular season, this is when the good teams start separating themselves from the pack. This is when good teams establish themselves as playoff teams and division winners, and start fighting for postseason byes.

But even teams likely to make the playoffs have holes. There's no perfect team in the NFL. And when a weakness is exposed, it can be difficult to cover up. After all, the NFL is a copycat league.

Three potential playoff contenders -- the New York Giants, New England Patriots and San Francisco 49ers -- put up subpar performances Sunday, even though the Patriots won (and the 49ers tied). It's by no means time to panic for any of these teams, but it's worth examining each team's key issues and whether they could remain come January.

Here's a look at key problems confronting the Giants, Patriots and 49ers.

New York Giants

A lot of people are bringing up fatigue as an excuse for this team, but I'm not buying that as a result of a Super Bowl victory. Yes, the Giants were one of two teams to play into February -- but the season started in September. They had plenty of time to recover during the offseason. However, it is fair to note that players have been thrown off their routines during the recent storm on the East Coast.

On the field, the Giants have two issues.