Next week’s big, nationally televised “Monday Night Football” showcase could feature a quarterback matchup of journeyman Jason Campbell of the Bears vs. untested Colin Kaepernick of the 49ers. Not exactly the creme de la creme of the NFC.

Why? Concussions, of course.

With so much attention paid to replacement refs and bounty ruling appeals this season, it’s an issue that’s slipped a bit under the radar lately. But it’s hard to ignore this: 25 percent of Sunday’s NFL games saw a starting QB leave with a concussion.