That season, Johnson served as rookie Brock Purdy's backup during an improbable playoff push. As 49ers fans remember all too well, San Francisco's Super Bowl hopes unraveled in the NFC Championship Game when Purdy suffered a devastating injury to his throwing arm against the Philadelphia Eagles.
Purdy was already the third quarterback to start that season after injuries to the two players ahead of him on the depth chart. But he wasn't the only signal-caller to go down in that playoff game. Johnson exited with a concussion — and, as he recently revealed, the situation was far more serious than previously known.
Speaking on the Ross Tucker Podcast, Johnson shared new details about the severity of the injury.
"Well, most people don't know that I was double-concussed in that game," Johnson said. "The first, if you ever have the time, and you really want to go back, you're going to notice the first sack I had was with a play-action pass, and Haason Reddick came off the edge, and he hit me, and my head hit the ground. I actually lost the ball on that play."
Reddick, notably, was also the defender who injured Purdy earlier in the game, leading to offseason surgery to repair a torn ulnar collateral ligament (UCL) in the quarterback's right elbow.
Meanwhile, the hit on Johnson resulted in his first concussion of the day. Because he had never previously suffered a concussion, he did not initially recognize the symptoms and remained in the game.
Later, veteran defensive lineman Ndamukong Suh delivered a second blow that caused another concussion and ultimately forced Johnson out.
"Two in one [game] — in the NFC Championship, the biggest game of my life," Johnson said.
He added that the damage was even more severe than many realized at the time.
"That was the start of, really, the decline of what was about to be that day," Johnson said. "I ended up with a brain bleed."