McCown, who turns 40 on July 4, spent the past two seasons with the New York Jets. He made the decision to retire after consulting with his family for the past few months. His body feels fresh -- he appeared in only four games last season -- but he decided to move on to the next chapter.
"I guess it just goes to show that you don't always get to choose your own path," McCown wrote. "But looking back, I'm proud of how my career has gone. I don't shy away from the journeyman label. I embrace it, full force.
"Because it's been one heck of a journey."
Later Monday, it was announced that McCown is joining ESPN as an NFL analyst. He will make his debut Wednesday on NFL Live.
"I am excited to make the transition into broadcasting with ESPN which will allow me to still be involved with the game I love. I look forward to bringing ESPN viewers the unique insights that I have gained throughout my career," he said in a statement.
McCown never was a star player in the league, but his career is extraordinary in its own right. He played for eight teams over 17 years, beginning with the Arizona Cardinals in 2002; in fact, he was the last player from the 2002 draft to still be active. He spent four seasons with Arizona, then played for Detroit, Oakland and Carolina. He also spent time with Miami and San Francisco, but never played in games for them.
After one season out of the NFL, McCown restarted his career with the Chicago Bears (2011 to 2013), enjoying a terrific 2013 season in which he threw 13 touchdown passes and only one interception.
He spent most of his career as the proverbial "bridge" quarterback, bouncing from one rebuilding situation to another. That was his role with the Jets; he also was heavily involved in mentoring Darnold.
After enjoying a career year in 2017, McCown lost his job in the preseason to Darnold, a first-round pick. It wasn't much of a competition. McCown spent nearly the entire preseason watching from the sideline as Darnold was given a clear path to the starting job.
McCown embraced his role as Darnold's mentor. When McCown re-signed in March 2018 (one year, $10 million), he knew there was a good chance the team would draft a quarterback in the first round. The Jets wanted him back because of his unselfish attitude and willingness to help young quarterbacks. It was costly from a financial standpoint, but it was "money well spent," Jets CEO Christopher Johnson said.
"I think it was just awesome to be able to learn and watch him," Darnold said of McCown, who lived in the same building as the young quarterback and spent countless hours with him outside the team's facility.
Well-traveled McCown was pressed into starting duty for three straight games when Darnold was out with a foot injury, weeks 10 to 12, but he wasn't able to recapture his 2017 form. He struggled mightily, completing only 54.5 percent of his passes for 539 yards, with one touchdown and four interceptions. The Jets lost all three games.
McCown signed with the Jets in 2017 after starting 22 games over the previous three seasons for Tampa Bay and Cleveland. He landed the Jets' starting job by default, as young quarterbacks Christian Hackenberg and Bryce Petty struggled in the preseason. McCown wound up setting career highs for completions (267), yards (2,926) and touchdown passes (18). The players voted him team MVP even though he missed the last three games with a broken hand.
"No matter what team I was on, I tried to serve it to the best of my ability, and I tried to influence my team in a positive manner," McCown wrote on The Players' Tribune. "I hope I did that. And I made sure that when my number was called, I was prepared, and I gave it everything I had, every time."
For his career, McCown has 17,707 yards, 98 touchdown passes, 82 interceptions and a 79.7 passer rating.