In previous years, losing WR Greg Jennings for an undisclosed amount of time due to surgery for a groin injury would be a big deal, but the Green Bay Packers have basically been without their top wide receiver already this season. He hasn't played at all in October, and over their last three games, QB Aaron Rodgers has thrown for 12 touchdowns and 1 INT. They'll be fine without him, which might be something to consider when Jennings becomes a free agent at the end of the year.
However the one area that has been a concern this season is the offensive line. While Rodgers had a great game against the Rams, the offensive line struggled to protect the QB and open running lanes for RB Alex Green. It seems like their problems every week can be traced to one player on the line, and against the Rams it was LG T.J. Lang.
His main problem was DT Michael Brockers, who despite having a quiet rookie season was great against the Packers. He had a sack in the first half when he shoved Lang into the backfield, and recorded two tackles for a loss on running plays (though one came when C Jeff Saturday couldn't block him). Overall, Lang appeared to allow two first half sacks, and missed on at least two blocks on second half running plays. Allowing that many plays in the backfield isn't good.
One strange thing was that they seemed to call for more runs to the left side although arguably their best lineman (RG Josh Sitton and RT Bryan Bulaga) play on the right. It was even more strange considering Lang's struggles, and some early game difficulties LT Marshall Newhouse, who had keeping up with DE Robert Quinn. At least Newhouse seemed to improve after the first quarter.
As long as I'm bringing up the bad, I should point out the good. The Rams's star DE Chris Long (13 sacks in 2011, 4 in 2012) was a non-factor and only recorded one tackle against the Packers. Mike McCarthy rarely gives his tackles any help in pass protection and Bulaga was great against the Rams' playmaker.