On average, Minnesota Vikings running back Adrian Peterson was one of the top three picks in fantasy football this season. However, he's been a bit all over the map so far and failed to deliver a quality return on your investment.

In standard scoring leagues, Peterson has topped 16 points or more three times, posted one ten-point game, and failed to score higher than six points twice. That's the definition of a feast-or-famine player, not a top three pick. The real bad news is that all of the data suggests that up-and-down trend will continue.

Peterson has been able to break off some long runs this year, totaling 45 fantasy points on rushing plays that go for 10 or more yards, according to ESPN NFL Insider KC Joyner. That's just one point behind current fantasy MVP Devonta Freeman. But when AP isn't busting long runs, he's failing to make a significant impact, as evidenced by his 3.9 fantasy points per game on carries that go for nine yards or less.

"These issues alone make Peterson a serious boom-or-bust back, but they are compounded by the recent decline in the Vikings' run-blocking prowess," Joyner wrote. "Minnesota had its worst showing this season in my good blocking rate (GBR) metric in Week 7. GBR measures how often an offensive blocking wall gives their ball carriers quality run blocking (very roughly defined as not allowing the defense to disrupt a rush attempt). The Vikings' 35.5 percent GBR was the first time they finished under the 40 percent league average and their 40.6 percent mark in Week 6 was barely above average.

"Add Peterson's age and career wear and tear to these other factors and it looks like it's time to trade him for a player who offers more consistency down the stretch."

The Vikings are a solid team at 4-2 and that always helps to boost fantasy value. But perhaps you should start thinking about selling high on Peterson if you're desperate for a roster shakeup.