Adam Thielen and Kirk Cousins know this: The Minnesota Vikings traded one of their top offensive weapons last week, sending wide receiver Stefon Diggs to the Buffalo Bills for four draft picks, including a first-rounder.

You can't blame the Vikings for making the move. That is quite a haul for Diggs, who probably isn't even a top 10 receiver in the NFL. But was it a wise decision?

Minnesota is coming off of a 2019-20 campaign in which it won 10 games and made it to the Divisional Round of the playoffs before losing to the San Francisco 49ers.

It was clear that while the Vikings were good, they were still a couple of pieces away from being legitimately scary. However, it was also obvious that Minnesota would not be able to make any substantial improvements this offseason given its unenviable salary cap situation, so the Vikings may have felt they would be better served cashing in on one of their best trade assets.

Here's the thing: Minnesota's offense just went from really good to just good.

The combination of Diggs and Adam Thielen was lethal in the aerial attack, but now, Thielen represents Kirk Cousins' only reliable receiver, which will allow defenses to double team Thielen and force Cousins to spray the ball elsewhere.

Now, it's not like the Vikings are bereft of offensive talent at other positions. Dalvin Cook is an elite running back, and Kyle Rudolph and Irv Smith Jr. comprise a pretty awesome duo of tight ends.

But not having Diggs takes away Minnesota's best vertical threat, which could severely compromise the offense and make it very predictable in 2020.

The lack of Diggs' downfield prowess could allow defenses to stack the box more and make life tougher for Cook, who has already had some knee issues as it is.

Without Diggs' big-play ability, Cousins becomes that much more easy to gameplan for, because opposing defenses know he doesn't have much of an arm. Thielen is terrific, but he is more of a slot guy and a possession receiver than a deep threat, and he is not much of a gamebreaker.

Not only that, but the Vikings don't even have a No. 2 receiver in general right now.

At the moment, it is probably Bisi Johnson, who logged 31 catches in his rookie year this past season. While he was a fairly pleasant surprise given that he was a seventh-round pick, I'm not sure how comfortable Mike Zimmer can feel about having Johnson as Cousins' No. 2 wide out heading into 2020.

Obviously, Minnesota can draft a receiver to rectify that problem, and you have to think that the Vikings will, indeed, use an early pick on a wide out.

But in an NFC North that houses the Green Bay Packers and the Chicago Bears, Minnesota has unquestionably taken a bit of a step back thus far this offseason.

With Diggs gone, the Vikings' ceiling just got a bit lower, and it's not like it was incredibly high even with Diggs on the roster.

Again, I can't necessarily blame Minnesota for trading Diggs for that package, but it is a move that will definitely have an adverse effect on the offense next season.