Raiders WR Darrius Heyward-Bey, who was knocked out by a helmet-to-helmet hit from Steelers safety Ryan Mundy, was at Raiders headquarters Wednesday but must pass NFL concussion tests before taking the field. (Getty Images)

Three days after being knocked out in a helmet-to-helmet hit by Pittsburgh S Ryan Mundy, Raiders WR Darrius Heyward-Bey spent time at team headquarters Wednesday.

“He’s doing good,” Raiders coach Dennis Allen said. “He was here today. He’s going through the protocol for NFL concussion testing, and we’ll let that process play out, and we’ll see when he’ll be available to us.”

Heyward-Bey, who suffered a concussion and a neck strain, spent Sunday night at Eden Medical Center for observation. He was released from the hospital Monday morning and is expected to make a full recovery.

“It really is mostly the concussion issue that’s the biggest concern,” Allen said.

Mundy reportedly was fined $21,000 for the hit, which did not draw a penalty flag.

“We don’t have any control over that,” Allen said. “We leave those matters up to the league.”

On the mend: Starting TE Brandon Myers suffered a fourth-quarter concussion Sunday and was a limited participant in practice Wednesday. He has yet to be cleared for contact, Allen said, but Myers said he’s encouraged by his progress and “absolutely” confident he’ll play Sunday at Denver.

“It felt good after the tests and everything,” Myers said. “I just wanted to get out there and run around, see how things go.”

The Raiders want to see Myers on the field Sunday. He has been targeted 15 times by QB Carson Palmer and caught all 15 passes.

Injury report: Heyward-Bey, CB Shawntae Spencer (foot), OT Khalif Barnes (groin) and DT Richard Seymour (knee) missed practice.

RB Darren McFadden (shoulder) was one of seven players limited in practice. The rest of the list: DT Tommy Kelly (knee), C/G Alex Parsons (shoulder), RB Mike Goodson (hamstring), K Sebastian Janikowksi (left groin), WR Rod Streater (eye) and Myers (concussion).

DB Michael Huff (knee) and TE David Ausberry (shoulder) were full participants.

Parting ways: Allen said it was a tough decision to waive second-year OT Joe Barksdale on Wednesday but that it was time to move on.

“Eventually, there’s a point in time where you move on from everybody,” Allen said. “It’s never an easy decision. There’s always a lot of thought that goes in. There’s only 53 spots with the best 53 guys that we think give us the best chance to win on Sundays.”

The Raiders used Barksdale’s roster spot to sign free agent DE Andre Carter.

Rating Peyton: During Allen’s media session, the topic turned to Broncos QB Peyton Manning. A questioner suggested that Manning might not be the player he once was, but was still “effective."

“I’m not falling into that trap,” Allen said. “He’s Peyton Manning. He’s a Hall of Fame quarterback. There’s no way that we’re going to, in any way, say that he’s not the same quarterback that he’s been. I’ve watched the tape. He’s still an outstanding quarterback.

“He’s operating that offense, and I don’t really see much of a dropoff of where he’s been before.”

Follow Raiders reporter Eric Gilmore on Twitter @CBSRaiders.