You know wide receivers are deep and running backs are scarce this year, right? Or do you just think you know that?

Sitting too close to the TV is terrible for your eyesight. Everyone knows this, as parents have ingrained it in their eager children for nearly half a century. Thereâ€™s just one small problem with this generally accepted fact. Itâ€™s not a fact.

Nope, the American Academy of Opthamology says that sitting too close to the TV wonâ€™t cause any physical damage to your eyes. Every TV made after 1968 is just fine for your eyesight, even if you sit really close. Thereâ€™s a difference between what you know, and what you think you know. It's the same in fantasy football.

The Myth of Wide Receiver Depth

The book on wide receivers versus running backs is the same this year as it has been in the recent past: backs are top-heavy, so you should grab them first. You can wait and still pick up quality wideouts. Here at NumberFire, weâ€™re in the business of using numbers instead of â€œthe book.â€ So what do the numbers say about wide receiver depth?

Last year, running back was actually deeper than wide receiver. Four wideouts topped 200 fantasy points. (Standard scoring, non-PPR leagues.) Compare that to 10 running backs. But the top tier alone doesn't signify positional depth. Surely there were many more viable fantasy receivers a rung or two below the top guys, right? Wrong. 12 WRs put up at least 170 points; 14 RBs did the same. 18 receivers put up 150 points, versus 19 backs. Only at the very bottom of the respective positions did wide receivers outnumber running backs and even then just barely: 25 receivers put up 130 points, as did 23 running backs.

Position Players over 200 points Players over 170 points Players over 150 points Players over 130 points RB 10 14 19 23 WR 4 12 18 25

But one year isnâ€™t a very large sample size. In 2011, the same trend - running back being deeper than receiver - held true:

Position Players over 200 points Players over 170 points Players over 150 points Players over 130 points RB 6 13 22 27 WR 4 9 16 22

Let's make it an even three-year sample size. In 2010, backs blew receivers out of the water.

Position Players over 200 points Players over 170 points Players over 150 points Players over 130 points RB 12 15 20 26 WR 4 8 16 22

So last year, running back was just slightly deeper than wide receiver. In 2011, the gap was even more pronounced. Same in 2010. What about this year? Despite basically everyone beating the drum for wide receiver depth, according to our projections, itâ€™s actually running backs who should have the deeper pool. Acknowledging that projections are an inexact science, we have eight backs projected to top 200 points, compared with just two receivers. Including the next tier, we have 17 running backs projected to top 170 points and 14 wide receivers set to reach that same mark. If anything, running backs appear to be the deeper class than receiver this season.

Calvin Johnson and Value

The true value of a first-round fantasy draft pick is in security. Unless you get a superlative year from someone like Adrian Peterson, as long as your pick ends up as a top 10 or so player at his position, you havenâ€™t failed. If you took a running back at 6 for instance, and he finishes the season as the 7th or 8th-best back, you shouldnâ€™t consider that a failure. This is fantasy football, and youâ€™re not a psychic; you wonâ€™t be able to predict exactly how guys will play so first round picks are all about minimizing risk while ensuring that youâ€™ll get a safe and productive player.

Thatâ€™s why Calvin Johnson is considered a first-round pick. Heâ€™s about as safe as it gets. Heâ€™s been the best wide receiver in football â€“ fantasy or otherwise â€“ for the past two years. He doesnâ€™t come with injury concerns, heâ€™s built like a tank, he plays for a team thatâ€™s going to throw the ball at least 35 times a game, and he doesnâ€™t really have anyone to vulture touchdowns away from him. If anything, he might be even better than he was last year, when he scored just five touchdowns thanks to somehow getting tackled inside the five-yard-line eight times. (That stat comes from Matthew Berry and ESPN Stats & Info.)

So thatâ€™s what youâ€™re getting with Calvin Johnson. And right now, you can get him with the 10th pick in your draft, on average, per fantasyfootballcalculator.com. But is he even more valuable than that?

Since heâ€™s clearly the top receiver, letâ€™s compare him to the top running back. Last year, Johnson put up 220.4 fantasy points. Adrian Peterson put up 307.4 points. There was a 22.2 percent gap in production between Johnson and the 10th-best wide receiver (Marques Colston, for those curious). There was a 34.0 percent production gap between Peterson and the 10th-best running back (Steven Jackson). Expand the sample size to the 20th-best player at each position and the production gap widens â€“ 36.4 percent for Johnson versus 51.5 percent for Peterson. This is all to say that Peterson separated himself more from his peers than Johnson did. Relatively, AP was the more valuable player last year.

Player Production Gap over 10th-best RB/WR Production Gap over 20th-best RB/WR Peterson 34.0% 51.5% Johnson 22.2% 36.4%

But Adrian Peterson had one of the greatest rushing seasons of all time in 2012, and Calvin Johnson had a down year touchdown-wise. Letâ€™s expand the sample size, and take a look at 2011 as well. That season, Johnson put up 263.2 fantasy points, best among wide receivers. Ray Rice was the leading fantasy back that year, with 296.8 points. Johnson delivered 35.7 percent more production than the 10th-best wide receiver that season (Vincent Jackson). Rice put up a 37.6 percent gap over Darren Sproles, 2011â€™s 10th-best running back. There was a 44.8 percent difference in production between Johnson and the 20th-best receiver. Compare that to a 46.6 percent production gap between Rice and the 20th-best running back.

Rice separated himself from him peers just slightly more, but the difference is basically negligible. In 2011 the best wide receiver was just as valuable as the best running back, relative to position. Thatâ€™s not even taking into account that many leagues start three wideouts versus two running backs, increasing the demand for receivers.

Player Production Gap over 10th-best RB/WR Production Gap over 20th-best RB/WR Rice 37.6% 46.6% Johnson 35.7% 44.8%

On top of all this, there's the fact that wide receivers tend to be much more volatile than running backs. But then there's Calvin Johnson, who provides consistent week-to-week production (he had just three "dud" games of under 5 fantasy points over 2012 and 2011 combined) that makes him even more valuable when compared to other wideouts. Even the most bullish Calvin Johnson fans wonâ€™t suggest you should take him number one overall, or even top three. (Unless youâ€™re in a PPR, three-WR league, in which case you might consider it.) But 10? Heâ€™s been comparably valuable, relative to his position, to the top running backs in the league the past two years, but youâ€™re going to pass on him to take C.J. Spiller? If youâ€™re sitting in that 4-9 range, you should take a long, hard look at Johnson. Think about what you know about depth and value, and then think about what you think you know.