GREEN BAY, Wis. -- At some point in the next 11 months -- likely sooner rather than later -- the Green Bay Packers will extend the contracts of receivers Randall Cobb and Jordy Nelson.

Between now and when they scribble their names on their new deals there will be much discussion about each player's value.

Myriad factors come in to play during contract negotiations, but the most important ones are production, injury history (which is usually tied to production) and age (which can be tied to injury history).

Another factor you might hear thrown around when it comes to Cobb and Nelson is the unscientific term "No. 1 receiver" -- as in should either one or both be paid like one?

In an ESPN Insider piece, former NFL scout Matt Williamson helped define exactly what that term means .

He came up with four characteristics:

They need to have the ability to separate from man coverage, understand how to find the soft spots in zones and have very strong athletic traits.

They need to be strong, fast and play big, which often -- but not always -- can eliminate shorter wide receivers from this equation.

They must be productive, even when opposing defenses are scheming to take them out of the equation; No. 1 receivers can be uncoverable and never come off the field.

They must display the above traits with consistency.

What was perhaps most interesting about Williamson's list is that he came up with only 14 players in the NFL who fit his criteria.

"The term 'No. 1 receiver' is often thrown around loosely, but to me, there certainly are not 32 No. 1 receivers in the league just because every team has a favorite target," Williamson wrote.

Also, Williamson had two tight ends -- New England's Rob Gronkowski and New Orleans' Jimmy Graham -- among his 14.

Among his 12 receivers, only four were among the NFL's top-10 highest-paid receivers (see the accompanying chart). They were: Detroit's Calvin Johnson (No. 1), Arizona's Larry Fitzgerald (No. 2), Chicago's Brandon Marshall (No. 6) and Houston's Andre Johnson (No. 8).

However, six of the 12 are still playing under their rookie contracts and will be in line for significant raises on their next deal.

Back to the cases for whether Cobb and Nelson belong in that same category as they enter the final season of their current contracts.

According to Williamson, one of them should be considered a No. 1 receiver and the other is close. Also, it's possible for one team to have two No. 1 receivers, Williamson wrote, as is the case with the Bears (Marshall and Alshon Jeffery).

The 6-foot-3, 217-pound Nelson cracked the list at No. 13 under the heading "Just ask their quarterbacks if they are No. 1 receivers." Williamson also put San Francisco's Michael Crabtree in that same category.

"With great size for the position, he is often mistaken for a possession weapon, however only three receivers converted more receptions of 20 or more yards last year, Williamson wrote of Nelson. "His deep speed and big-play ability is vastly underrated, but Nelson also is Aaron Rodgers' go-to target when Rodgers needs a first down and has always proven to be reliable.

"Nelson had his best season in 2013, accumulating over 1,300 receiving yards, and bear in mind that he was playing without Rodgers for much of that time. He isn't a product of the system or his surroundings and would be great in any environment."

Nelson's next contract will be his third. Midway through the 2011 season, he signed a three-year extension that averaged $4.2 million per season. That average ranks 32nd among all NFL receivers in 2014.

Williamson ranked Cobb among 11 players who he termed as "close but not quite" No. 1 receivers.

Cobb, who like Nelson was a second-round pick, is entering the final season of his rookie contract. Two factors likely kept Cobb out of Williamson’s top 14: his size (5-10, 192) and that he missed 10 games last season because of a fractured tibia.

But in 2012, Cobb caught 80 passes despite missing one game, and there is room for growth. He is entering his fourth season but won't turn 24 years old until late in training camp this summer, making him more than 5 years younger than Nelson, who turns 29 in May.