GREEN BAY, Wis. -- Aaron Rodgers isn’t injured -- or so he says. So what’s wrong with the Green Bay Packers quarterback?

Coach Mike McCarthy said if anything, Rodgers is trying to do too much.

Can that really explain why the Packers’ offense is headed for all-time lows under Rodgers in yards (344.3 per game) and passing yards (236.3)?

After a 6-0 start, the Packers have lost three straight starts with Rodgers at the helm for the first time since 2008, his first year as a starter.

Here are five reasons the reigning NFL MVP has struggled:

Whatever the reason, it's clear that Aaron Rodgers and the Packers' offense are struggling right now. AP Photo/Matt Ludtke

No Nelson: The loss of Pro Bowl receiver Jordy Nelson has created a trickle-down effect. Not only did Rodgers lose his deep-threat target, but it has allowed teams to put their top cover cornerback on Randall Cobb, James Jones or Davante Adams. Rodgers hasn’t thrown a single touchdown pass on a throw that has traveled 30 or more yards in the air and has completed only five such passes all season, according to ESPN Stats & Information. Last year, he threw seven touchdowns on balls that went at least 30 yards in the air. From 2011-2014, Rodgers threw 20 touchdowns on such passes. Nelson was so good on deep out passes, among other routes. Rodgers tried to throw one to Cobb in Sunday’s loss to the Lions, and Cobb couldn’t haul it in. It’s much tougher for a 5-foot-10 receiver such as Cobb than it is for the 6-3 Nelson to make that play. Rodgers has completed just 48.8 percent of his passes to receivers the past three games, a figure that was at 70.0 percent in the first six games.

Nothing for free: Early in the season, Rodgers feasted on free plays. He’d catch opponents with 12 defensive players on the field or get them to jump offside. In the opener against the Bears, he hit Jones for a 34-yard completion on a free play. The next week against the Seahawks, he had a 22-yard pass to Cobb, a 29-yard touchdown to Jones and picked up a 52-yard pass interference penalty all on free plays. The next game against the Chiefs, he threw a 27-yard touchdown pass and had a 52-yard completion -- both to Jones -- on free plays. The last time the Packers hit on a free play was a month ago, when Rodgers completed a 46-yard pass to Jeff Janis against the Chargers. He has gone three games without taking advantage of one.

Play-calling changes: Rodgers claims he loves having his longtime quarterbacks coach and offensive coordinator Tom Clements as his playcaller, something McCarthy apparently doesn’t plan on changing. But other than the loss of Nelson, it’s the only major change from last season, when Rodgers won his second NFL MVP award. Before McCarthy handed those duties to Clements for this season, Clements hadn’t called plays in more than a decade, not since a two-year stint as the Bills’ offensive coordinator in 2004 and 2005.

He really is injured: At one point during Sunday’s loss to the Lions, Rodgers reached down to grab his foot. Later in the game, he took a shot to his left knee from defensive end Ezekiel Ansah. Rodgers insisted after the game that he's healthy, but he was short when asked about it two different times. Rodgers' past two seasons have been impacted by injuries -- the broken collarbone in 2013 and the calf injury last season. He missed seven games because of the collarbone but played through -- and played well with -- the calf injury. As McCarthy said after the Lions game, Rodgers has gotten hit “way too much.” In the past three games, Rodgers has been sacked 11 times, equaling his total in the first six games.

Possible off-field issues?: A longtime NFL agent told me recently that when he sees one of his top-performing clients play differently, as Rodgers has of late, the first thing he wonders is if something is going on in his personal life. There’s no indication that Rodgers’ relationship status has changed. Lions reporters said they spotted Rodgers’ girlfriend, actress Olivia Munn, at Lambeau Field on Sunday. Sometimes it's easy to forget that professional athletes have lives away from the field, and you never know what could be going on in their personal lives.