[RandallBrown]

https://operations.nfl.com/the-rules/rules-changes/nfl-jerse...

Linemen are required to wear higher numbers so it's no surprise that people automatically associate higher numbers with bigger people.

[singleshot_]

When I showed up for double sessions freshman year, I found that the sizes of the shirts corresponded to the numbers. Even without rules about what number an interior lineman must wear, the big body positions just aren’t going to physically fit in jersey number three.

[the_snooze]

I've always associated single-digit numbers to "skill positions," especially speedsters like WRs, RBs, and CBs. If you're in the 50s and above, I'll assume you're one of the "big uglies" duking it out in the trenches.

[jghn]

At least in the NFL WRs and TEs have traditionally been in the 80s. The shift towards the teens and lower started in the mid-aughts.

[kaesar14]

Specifically a rule change that allowed this - too many teams had 80 numbers retired.

[dpeck]

A lot of LBs in the 40s and 50s. I’d qualify those more as medium sized (but meaner) uglies :)

[kleinsch]

Read the article

> When we looked at the relationship between the ratings of size and slenderness and the numbers, [and] we did a very small range, like from 17 to 19, we see a very robust correlation."