Detroit Lions wide receiver Calvin Johnson has long been the consensus answer when asked who the best receiver in the NFL is. That's what happens when you post five straight seasons with at least 1,000 yards. But Johnson, who will turn 30 in late September, is coming off his least productive season since 2009.

Johnson, hampered by leg injuries all season, appeared in just 13 games last year and caught 71 passes for 1,077 yards and eight touchdowns. By any normal player's standards, that's a good season. But it is decidedly un-Megatron like. As a result, ESPN NFL Insider KC Joyner believes he is being overvalued in fantasy football.

"How much risk is too much risk when it comes to taking someone in the first two rounds of a fantasy football draft?" Joyner wrote. "That's the question that must be answered when considering whether to take Megatron with a top-20 selection.

"Johnson's talent level is such that he has been able to rank fourth in wide receiver fantasy points per game the past two seasons (13.4) despite battling a multitude of injuries.

"This ability to overcome physical ailments may give fantasy owners a false sense of security as to Johnson's durability. ESPN Insider Mike Sando reported a few months ago that an NFL executive (not with the Lions) said that it was possible that Johnson could physically 'fall apart at some point.'

"That point may not be this year, but it does bring to mind this question: Should a fantasy owner be willing to risk a second-round pick on a player with this level of uncertainty? Some fantasy team owners may say yes, but the suggestion here is to let someone else take that risk and instead value Johnson as a high-tier WR2."

At the moment of this writing, Johnson appears fully healthy and has impressed MMQB's Peter King with his playmaking in training camp. However, it should be noted that Lions QB Matthew Stafford attempted the fewest passes last year in any 16-game season he has played in. Golden Tate's emergence and the addition of second-round running back Ameer Abdullah also point to a lighter workload for Johnson in 2015. All told, Detroit appears to be headed towards a more balanced offensive attack.

Joyner may be airing too much on the side of caution, but he's right to point out the handful of question marks that surround Calvin Johnson this year. Johnson is no longer the universal top WR in fantasy and it's fair to wonder if his upside is curbed just a bit this year.