Rookie WR Nathan Palmer shines: When coach Jim Harbaugh went to the defense of A.J. Jenkins on Sunday, he said he felt the 49ers’ group of young receivers is the best he’s ever been a part of in football as a player or coach. After two days in pads, it’s too early to make definitive statement on the group one way or the other, but it’s clear the team has found a gem in undrafted rookie Nathan Palmer.

“He’s done a good job here learning the system,” Harbaugh said. “Had an excellent day [Sunday]. That really stood out to all of us.”

The Northern Illinois product has looked every bit the part of an NFL receiver so far. If it weren’t for the team’s depth at the position, he’d be a candidate to contribute right away. The 49ers will be lucky if they can keep him on their practice squad and off another team’s active roster.

Leonard Davis firmly in competition at RG: Alex Boone has done nothing to indicate he isn’t ready to make the jump to starting RG, but with the addition of veteran Leonard Davis, there promises to be an intense competition for the job.

“Doesn’t look like there’s any rust there,” Harbaugh said of Davis. “I think that he’s been working really hard with [OL coach] Tim Drevno. The two of them are meeting extensively and Leonard’s coming along real fast, getting up to speed with the system.

Davis has shown impressive mobility for his size. The 49ers list Davis at 355 pounds, which makes him 24 pounds heavier than the next biggest guy, LG Mike Iupati.

LT Joe Staley described Davis about as well as possible: “He’s a huge human being.”

Crabtree misses third-straight practice: WR Michael Crabtree did not practice for the third-straight day Monday with what is apparently a strained calf muscle. The injury is not expected to keep Crabtree, who has never played in a preseason game, out for a significant amount of time.

Rookie RB Jewel Hampton likely out for six games: Undrafted rookie RB Jewel Hampton is expected to miss at least the first six games of the season after undergoing surgery to remove a bone spur, according to Harbaugh. He will begin the season on the Non-Football Injury list.

Brian Tyms bounces back: Undrafted rookie WR Brian Tyms had a welcome-to-the-NFL moment Sunday when he shoved fellow rookie Trenton Robinson to the ground. The stunt led to him getting kicked out of practice by Harbaugh and a 1-on-1 chat with the coach following practice. Harbaugh addressed the incident Monday: “Yeah, it was an incident that, just the way we do things, how we do them, just didn’t meet that standard. It was well below it and we addressed it. I think we’ll handle it better going forward.”Demarcus Dobbs

Demarcus Dobbs shows he can catch: DL/TE Demarcus Dobbs’ future on offense might not be limited to blocking. In a 7-on-7 drill in practice Monday, Dobbs -- wearing No. 96 -- fully extended his arms to make a tough catch look easy.Joe Hastings

Joe Hastings sits out: WR Joe Hastings did not take part in practice Monday after appearing to have strained his right hamstring in practice Sunday. Hastings came up limping and grabbed his hamstring while covering a punt early in practice. He stayed on the field for the remainder of practice, but did not participate.

Follow 49ers reporter Kyle Bonagura on Twitter: @CBSSportsNFLSF and @KyleBonagura