ESPN NFL

Posted by ESPN.com's Mike Sando

SANTA CLARA, Calif. -- The 49ers' afternoon practice concluded with team medical personnel steadying Chilo Rachal and guiding the starting guard to a cart for a ride into the training room.

The initial diagnosis was an unusual one: headache. Rachal wore a towel over his head and sat in the cart's passenger seat. The 49ers will evaluate him further.

The 49ers' other starting guard, David Baas, will undergo additional tests Wednesday on the foot he strained during nutcracker drills Tuesday morning.

Others notes from the fourth 49ers practice I've watched since arriving in Santa Clara late Sunday:

• Those who requested information on linebacker Scott McKillop should know he's going through what most rookies experience, a transition. I watched him charge toward the hole to stop a running play, only to take the wrong angle, buckle and fall to the ground as Glen Coffee burst into the secondary. Later, McKillop broke up a short pass to tight end Vernon Davis.
  
• Speaking of Davis, he continued to catch everything thrown his way, but he did lose a fumble when cornerback Marcus Hudson popped the ball free.
• The offensive linemen seemed to fare better on the whole during pass-rush drills. Outside linebacker Manny Lawson seemed to know instantly that he'd made a mistake against left tackle Joe Staley. Lawson yelled out in frustration while the drill was ongoing. Staley froze Lawson and controlled him convincingly on the play. One exception: Justin Smith, perhaps fresh after sitting out the morning session to save his veteran legs, drove Tony Wragge into the quarterback area with a powerful punch.
• Evaluating right tackle Marvel Smith can be difficult because the 49ers are limiting him to one practice per day. Even when Smith practices, he shares reps with Alex Boone.
• Defensive end Kentwan Balmer participated in inidividual drills after spraining his left knee in the morning session, a good sign for the team.

I'll be going through my notes and audio files to process interviews with multiple players conducted over the last couple days. Back at 49ers camp Wednesday before heading to Seattle for a few days with the Seahawks, followed by a trip to see the Rams.