Since 1966, only one under-30 quarterback has had as good a year as Colin Kaepernick’s 2016 has gone unsigned the next year.
Due to Kaepernick's protest of the national anthem last season, there have been questions as to whether that's the reason teams have been avoiding him.
It’s difficult to find a recent free agent quarterback who played at Kaepernick’s level and lasted so long on the market the next offseason. Matt Leinart (2012) and Kyle Orton (2014) signed nearly 50 days into their free agency, but neither had played much the year before. Michael Vick wasn’t signed for 169 days in 2015, but he was also older and coming off a season (39.4 QBR) far worse than Kaepernick’s 2016.
Beyond the political component of Kaepernick's situation, there is an unusual factor this offseason in that Tony Romo's status remains uncertain.