SANTA CLARA - After a very promising finish to his rookie season, 49ers cornerback Ahkello Witherspoon seems to be in a sophomore slump. 

When Jimmie Ward left Monday’s game in the fourth quarter with a hamstring injury, the unexpected happened. Greg Mabin took his place at cornerback instead of Witherspoon. That was the plan all week, according to 49ers coach Kyle Shanahan. 

“Jimmie practiced all week as our starter,” Shanahan said, “and we gave Mabin the backup role. So we knew going into the week that Ahkello was going to take the backseat. We had him get a little more scout-team reps and challenged him that way, and he was up to the challenge.”
 
Witherspoon’s snap count has gradually gone down over the past few weeks. This was apparent in Green Bay when he played no snaps on defense for the first time all season. He was limited to just nine special-teams plays, including the Packers’ game-winning field goal as time expired – a play on which he collided with Mabin and sustained a concussion.
 
The previous week, facing the Arizona Cardinals, Witherspoon played 29 defensive snaps and 11 on special teams. Facing the Chargers, he played 51 defensive snaps and two on special teams. 

Witherspoon’s regression has even Shanahan stumped. When asked about why he has taken a step back he couldn’t specify what has happened. 

“I’m not sure,” Shanahan said. “That’s something we’re working through with him. I do think he had his best week of practice last week, which I had a good talk with Ahkello about that before the game. It was the most encouraged we had been with him, last week through practice.

 

"I think Ahkello will be there, exactly where he was at last year. I expect him to get better from that. It hasn’t happened right away, but he’s going in the right direction now and I expect it to continue.”

The third-round pick from Colorado received high praise from veteran cornerback Richard Sherman during the offseason. The three-time All-Pro invited Witherspoon to his first “Cornerback Summit” down the road at Stanford. He spent two days learning from the likes of Darius Slay, Xavier Rhodes and Aqib Talib.

Sherman spoke about his belief in Witherspoon being among next great cornerbacks and how he knew he could handle his own with the assembled group. So what has changed? 

Is it because Sherman is now on the other side of the field, which makes opposing quarterbacks target the other side? Is it because Witherspoon’s confidence became too high after so much praise? Is it just the growing pains of being in the NFL? 

There isn’t a concrete answer yet, and there may not be one for a little while with Witherspoon unable to practice while in the NFL’s concussion protocol. The time table for his return to practice is unclear for now.

Mabin, who struggled in his limited role on Monday, is likely to be back on the field in an expanded role if Ward and Witherspoon can’t play on Sunday against the unbeaten Los Angeles Rams.