Kaepernick faced a locker-room split, per Rapoport. The organization's decision makers stayed with the 2012 breakout star as long as they could, but dysfunction on offense could no longer be ignored.
After insisting just two weeks ago that there was no controversy and "Colin's our quarterback," Jim Tomsula reversed course on Monday, acknowledging that the coaching staff is "evaluating everyone."
Kyle McLorg of Bay Area Sports Guy first reported Kaepernick's benching.
Kaepernick is a clearly regressing quarterback who has struggled not only with the rudimentary passing elements such as accuracy, anticipation and touch, but also with protections, field vision and decision making. His startling lack of field vision and awareness in Week 8 was perhaps the last straw.
This is a stunning fall from grace for a quarterback who was held up by ESPN analyst Ron Jaworski as a future superstar with the skill set to become one of the greatest of all time.
Defenses have since adjusted to the read-option, leaving the hyper-athletic Kaepernick to cope with the metamorphosis from a college spread offense to consistently delivering the ball and running his offense from the pocket.
Turning to a quarterback with Gabbert's uninspiring track record is tantamount to throwing in the towel on a lost season after watching 1,000 snaps, 20 Pro Bowl appearances and three respected coaches walk out the door over the past 10 months.
Squarely in rebuilding mode, general manager Trent Baalke will have to decide next offseason if Kaepernick is salvageable or broken beyond repair.