The passing attack didn't quite pan out as the Vikings expected in 2015 after they added deep threat Mike Wallace in an offseason trade with the Dolphins and got a healthy Kyle Rudolph back in the offensive huddle.

That, of course, isn't all on the pass-catchers. Pass protection was poor and quarterback Teddy Bridgewater was inconsistent at times. But needless to say, Wallace and fellow Week 1 starter Charles Johnson disappointed.

Wallace, who earned $9.9 million, had career lows with 39 catches, 473 yards and two touchdowns. Johnson, meanwhile, lost his job to surprising rookie Stefon Diggs and by season's end was a weekly healthy scratch.

Like Johnson, former first-round pick Cordarrelle Patterson was also a total non-factor for much of the season. Again displaying little attention to detail, he fell behind Jarius Wright and Adam Thielen on the depth chart.

At the tight end position, Rudolph was asked to block a little more often in 2015 than he had in recent seasons, which partially explained his modest production. He led the Vikings with five touchdowns, but the expectation was that he would contribute more than just 495 receiving yards.

Two of the biggest bright spots came from the draft class. Diggs burst onto the scene to lead the team with 52 catches and 720 yards. Fellow fifth-round pick MyCole Pruitt showed promise, too, from the tight end position.

Still, despite the addition of those two to the pass-catching corps, upgrading the wide receiver position should be one of the team's top two priorities this offseason, along with getting the offensive line straightened out.

Vikings free agents: Tight end Rhett Ellison is the only unrestricted free agent. The Vikings value his blocking and versatility, so he is a candidate to re-sign. Thielen will be retained as an exclusive rights free agent.

Level of need: High. Diggs has long-term starting potential and Wright is a reliable slot receiver. But the Vikings are still seeking that true No. 1 wide receiver, something they haven't had in a long while. Specifically, they need a bigger receiver who can make contested catches down the field. Alshon Jeffery could be awfully tempting if the Bears let him reach free agency. There are also options in the draft, though this class of wide receivers is not as stacked as those from 2014 and 2015, according to draft analysts.

Stat that stands out: six — passes gaining 40-plus yards for the Vikings in 2015. Only the Cowboys produced fewer big plays in the passing game.

Burning question: Is there any chance that the Vikings will actually keep Wallace around? Coach Mike Zimmer praised him for his professionalism after the season. "I would like him back," Zimmer said. "I just love the kid." But he also acknowledged that the future is uncertain for Wallace, who is set to make $11.5 million in 2016. The Vikings can release him without any salary cap ramifications. Or they could ask him to take a pay cut, but if you are Wallace, do you want to come back after being underutilized here? It is hard to imagine Wallace remaining in Minnesota, but you never know.

Check out the Access Vikings blog tomorrow for a look at the offensive line.