Four years ago, Colin Kaepernick was moments away from winning a Super Bowl with the 49ers. Last season, he split time under center with Blaine Gabbert on a team that managed just two wins, and now Kaepernick is a free agent.

The reasons he remains out of work vary depending on who you ask. It's either because he's no longer the player he was when Jim Harbaugh was his coach and mentor in San Francisco or, more ominously, Kaepernick has been informally blackballed for his stance on social-justice issues. It started during the 2016 preseason when the quarterback would take a knee during the national anthem, his form of protest against social inequality.

Meanwhile, every free-agent quarterback signing not named Kaepernick reignites questions about why the former 2012 second-round pick can't find work. Giants co-owner John Mara offered insights into why this is.

"All my years being in the league, I never received more emotional mail from people than I did about that issue," Mara told's Jenny Vrentas. "If any of your players ever do that, we are never coming to another Giants game. It wasn't one or two letters. It was a lot. It's an emotional, emotional issue for a lot of people, moreso than any other issue I've run into."

Mara said the Giants never discussed signing Kaepernick, mostly because they were focused on finding Eli Manning's eventual long-term replacement (the team addressed that need when they drafted Davis Webb in the third round).

For now, Kaepernick remains a quarterback without a team, but in recent days there have been reports of mutual interest between him and the Seahawks, where'd he serve as Russell Wilson's backup.