NFL player reliance rankings

Calvin Johnson's role has been reduced in Detroit, while Adrian Peterson continues to carry the load. Getty Images

By any measure, Calvin Johnson was pretty good last year.

Maybe the 122 catches jump off the screen, given 20 other wide receivers even had 122 targets. Johnson topped the century mark in receiving yards in 11 of 16 games, something only Michael Irvin was able to do. But what made it most impressive was the way he did it without any help.

Every Sunday, Johnson was the focal point of the Lions' offense. Even with all the defensive attention, he accounted for almost 30 percent of the Lions' yards from scrimmage, the highest percentage by a wide receiver since the start of 2006. The next-closest Lions receiver was Titus Young, checking in 84 spots lower at 5.9 percent.

The 50-yard line of the season is a good place to evaluate the production of the league's skill players beyond just rushing and receiving yards. The 2013 Midyear Performance Rankings give us a look at which nonquarterbacks have meant the most to their teams not just in presence, but production entering Week 9.

There are five components to the rankings, all factoring in three basic goals of an offense -- move the chains, finish drives in the end zone and don't turn the ball over.

How we calculate the rankings: The question we answer -- how much of a team's overall production has each player accounted for? The rankings take into account both a player's percentage of his team's yards from scrimmage and points scored. Second, how has each player performed on third and fourth down? Both conversion percentage and opportunities (targets plus rushes) as a percentage of the team's snaps are factored in. Finally, turnovers are accounted for. Packaging them all together produces our Midyear Performance Score. An (impossible) perfect score would be 100, meaning a player would have had all of a team's yards and points without a fumble while converting all of his team's third- or fourth-down snaps for a first down.

Run the numbers and you have a familiar name making a huge impact in the NFC North. And it's not Calvin Johnson.