LANDOVER. Md. -- The Minnesota Vikings' trade for Sam Bradford on Sept. 3, when the team sent a first-round pick and a conditional 2018 fourth-rounder to the Philadelphia Eagles in the wake of Teddy Bridgewater's injury, initially looked like a bold masterstroke that could keep intact the Super Bowl hopes of a promising team.

Now, it's the only thing keeping the Vikings' offense afloat in a season that's quickly taking on water after Sunday's 26-20 loss to the Washington Redskins, Minnesota's fourth setback in a row after five straight wins to open the season.

Sam Bradford threw for 307 yards and two TDs, but it wasn't enough as the Vikings fell 26-20 to the Redskins on Sunday for their fourth straight loss. Rob Carr/Getty Images

The Vikings' ability to move the ball Sunday was again, as it has been for much of the season, almost solely dependent on Bradford's sufficiency as a quarterback. He'd rallied them from a 14-0 deficit, with three scoring drives in the second quarter that gave the Vikings a 20-14 halftime lead, on a diet of short crossing routes that preyed on the Redskins' zone structure at times and their man-coverage skills at other times. He'd connected on 24 of his first 29 passes, moving the Vikings into Redskins territory even as Washington defenders came perilously close to timing their jumps on several of Bradford's throws.

Then, the turnover the Vikings couldn't afford happened. Preston Smith tipped a Bradford throw meant for Adam Thielen on a quick slant and came down with it for his first career interception to set up a drive that would put Washington up 26-20 with 2:31 to play and bleed the Vikings of their timeouts. Bradford's one mistake was one too many for a team that can't afford any from him right now.

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The Vikings haven't run for more than 104 yards in a game this season and have crossed the 100-yard mark only once, back in Week 4 against the New York Giants. After Bradford carved up the Redskins for 160 yards in the second quarter alone, the Vikings gave Matt Asiata the ball on five of their first eight offensive plays in the third quarter, netting a total of 9 yards on those five runs. Their leading rusher Sunday was Jerick McKinnon, with 16 yards, and Thielen's one run for 11 yards put him third on the team. Their attempt to come back for the game-winning score, on a drive predicated on short throws from Bradford to Stefon Diggs, imploded with two sacks and a holding penalty in three plays -- and left tackle Jake Long was carted off on the Vikings' penultimate offensive play.

Defensively, a team that had pressured quarterbacks on 31.7 percent of their dropbacks through the first five weeks -- the third-best figure in the league -- has created pressure only 19.6 percent of the time over the last three weeks and sacked Kirk Cousins just once Sunday.

Some of this isn't anyone's fault. The Vikings have been riddled with injuries on offense in a fashion that's required them to conduct almost a weekly inventory of what they can do to be productive on that side of the ball. Their offensive line, which has been permeable against a pass rush and ineffective while run blocking, could need another adjustment if Long is out. But Bradford knows all too well how quickly seasons can dissolve when things go awry around a quarterback. With the Vikings' losing streak now at four games, he could be on his way to another painful reminder of that fact.