Three years ago at about this time, the Green Bay Packers were coming off a Super Bowl victory and embarking on a landmark season. They’d eventually become only the sixth team in NFL history to win 15 or more regular-season games. And while Green Bay’s campaign ended on a sour note, with an upset loss to the New York Giants in the divisional playoffs, the Packers had already won Super Bowl XLV with their current core of players (including the ever-coveted elite quarterback in Aaron Rodgers) and seemed poised to contend for even more over the next five to 10 years.But since the end of the 2011 regular season, the Packers have won 21 games, lost 17 and tied once (including the postseason), a record that would be a toss-up to make the playoffs most years. They went through a seven-game stretch without Rodgers last season, during which the team went 2-4-1. But even with Rodgers at the helm over the past three seasons, the Packers have won just 19 of his 31 starts — only good for about 9.8 wins per 16 games. That includes a 1-2 start to current season and the 19-7 egg they laid Sunday against the Detroit Lions.So, what happened? The Packers had used a historically great passing game to paper over other weaknesses. But Green Bay’s passing game hasn’t been elite this season. The luster is gone.The Lions have shown all the earmarks of a good defense in the early going this season, but it’s hard to imagine an offensive group as talented as the Packers mustering just 147 net passing yards and a measly 223 total yards against Detroit. The Lions combined outstanding run defense (Green Bay’s rushing plays cost them a staggering 10.37 expected points, according to Pro-Football-Reference.com) with opportunistic pass-rushing (they only pressured Rodgers five times per Pro Football Focus’s numbers but had two drive-killing third-down sacks). Detroit also limited Green Bay “explosives” (none of their 51 plays gained more than 18 yards), holding the once-vaunted Packers’ offense to a single touchdown.Even when Green Bay was at their best in 2011, they relied heavily on Rodgers and the passing game. The Packers posted the league’s top record and second-best point differential despite a defense that allowed the most passing yards in NFL history and a running game that was little better than average on a per-play basis. Rodgers earned MVP honors by spearheading the league’s best aerial attack in a season that rewrote the passing sections of the NFL record book.According to a Value Over Replacement Player (VORP) score I created based on Pro Football Focus’s player grades, Rodgers accounted for a larger proportion of his team’s total value than any of the other popular MVP candidates in 2011.But this year, Green Bay is scoring only 18 points per game, and Rodgers ranks just 18th among qualified quarterbacks in adjusted net yards per attempt (ANY/A) thus far. Granted, that number has come against an above-average slate of pass defenses — headlined by the Legion of Boom opening night — but he’s still only 10th in the league if we use the ANY/A allowed by each opponent last year to set up an expected level of performance in each game.Rodgers’s completion percentage is down — despite settling for shorter completions than in the past — and he’s also taking more sacks. But it’s not all the QB’s fault. In 2011, he had a pair of very good wide receivers in Greg Jennings and Jordy Nelson; this year, Nelson has been tremendous and that’s about it. Randall Cobb, the Packers’ fourth wideout last year (by targets), has been pressed into No. 2 duty. The results haven’t been great. In PFF’s estimation, Nelson and tight end Andrew Quarless have been Rodgers’s only above-average targets so far.And the Packers’ running game has provided even less support than usual, ranking 29th in the NFL if we sum and normalize their PFF rushing and run-blocking grades. You don’t need fancy stats to see they’re also averaging 3.6 yards per carry, despite running an array of draws and delays in an attempt to capitalize on the respect afforded Rodgers and the passing game.It’s still quite early to definitively boot the Packers out of the Super Bowl contender pool, but their Elo rating (1481) is below the league-average of 1,500 — the lowest it’s been since losing to a formerly winless Tampa Bay Buccaneers squad in Week 9 of the 2009 season. Rodgers and company rallied from that loss to win seven of their next eight games to close out the regular season, but it remains to be seen whether this Packers team has a similar recovery in it.