Why did Amari Cooper have to change jersey numbers with the Buffalo Bills?

Former Alabama All-American Amari Cooper will wear number 18 in his first game with the Buffalo Bills on Sunday afternoon. Wide receiver Davante Adams will make his New York Jets debut at number 17 on Sunday evening.

Both Pro Bowl pass catchers were traded last week, with Cooper going from the Cleveland Browns to the Bills and Adams going from the Las Vegas Raiders to the Jets. But Adams was allowed to keep the number he has worn throughout his NFL career, while Cooper will wear his fourth NFL number.

RELATED: AMARI COOPER ON TRADE: “IT REVIVED ME”

Asked about his new number at his introductory press conference, Cooper indicated it had no special meaning, but said he only had a choice between two numbers, which is true if the wide receiver wants to keep a number in the single digits or in the tens. When Buffalo acquired Cooper, the only unused numbers from 0 to 19 were 16 and 18.

Cooper wore number 2 for the Browns. Kicker Tyler Bass wears No. 2 for the Bills. Players regularly give away jersey numbers to new teammates who are more established in the NFL, sometimes in exchange for financial gratitude.

But Cooper couldn't have even bought the number from Bass because NFL rules prohibit players from changing their numbers during a season without changing teams.

“For competitive reasons, no player may change his jersey number once the regular season begins,” the rule states. “Players on the practice squad who were not on the active roster for a regular season game may change their jersey numbers to make an approved number available for a new player on the active roster.” Specific exceptions to this rule may vary depending on the Circumstances may be considered by the NFL Football Operations Department (e.g., if a player has transferred to another team).”

There was no exception for Cooper, just as there was none when he was traded from the Raiders to the Dallas Cowboys during the 2018 season. In this case, he moved from No. 89 to No. 19 because tight end Blake Jarwin was already in the 89 for the Cowboys.

The Bills have players in the 19 and 89 — wide receivers KJ Hamler and Jalen Virgil, respectively — but they are on the practice squad, so those numbers were available by rule if Cooper tried to work out a change.

The number 9 that Cooper wore at Alabama will be worn in Buffalo by safety Taylor Rapp.

The NFL made an exception to its number rule for Adams.

When New York acquired Adams, rookie wide receiver Malachi Corley wore the number 17 jersey. But Corley will wear number 14 on Sunday night, while Adams will wear the number 17 jersey on Sunday night against the Pittsburgh Steelers.