Let's be clear: The biggest difference between the 2012 Vikings, who started 4-1, and the 2013 Vikings, who started 1-4, is defense.
When a team has allowed twice as many points (158 this year vs. 79 last year) through five games, the primary culprit is clear.
But here's one name that doesn't seem to be brought up enough when it comes to explaining the record flip-flop: Percy Harvin.
Remember him? He had 407 receiving yards through five games last season, with at least 80 yards in all but one. In the lone game he didn't hit that mark, he ran a kickoff back 105 yards for a TD in a victory over Detroit. He was a first-half NFL MVP candidate before he got hurt. Harvin had 528 yards receiving after the catch last season despite playing just nine games.
He was a game-changer. A mercurial guy, but a game-changer.
The Vikings, emboldened by winning four consecutive games without him down the stretch and leery of giving him a big contract, traded him to Seattle in March for a first-round draft pick and a couple of lesser picks. It looked good as people grew excited for the Vikings' three first-round picks. It looked better for the Vikings when Harvin was injured (he's still yet to play a down for Seattle).
But let's not forget just how big of a role he played in launching the Vikings toward the playoffs last year. He was more valuable than Adrian Peterson in the first half of the season. He allowed for an incredibly safe passing game — just two INTs through five games last season, vs. seven this year — because of what he could do after the catch.
Let's also not forget that the Vikings won four games down the stretch without Harvin largely because Peterson became superhuman during that time, running for 651 yards in those games.
The Vikings receiving group this season is better, collectively, than it was a season ago. But they don't have a Harvin type (or at least aren't using anyone consistently as a Harvin type). In their losses this year — most of them winnable games in the fourth quarter — the Vikings have missed him.