SANTA CLARA – When 49ers tight end Colin Cloherty had his exit interview with general manager Trent Baalke in January, the message was blunt: Get bigger. Get stronger.

Cloherty, who played at Brown and who spent part of 2009 with the Colts, was very much in the mold of Indianapolis tight end Dallas Clark – a good runner, a talented receiver but not much of a blocker.

Cloherty took Baalke's directions to heart and headed to Carini's House of Iron in Pine Brook, N.J. The gym's namesake, Joe Carini, is a former competitive weightlifter (he once squatted 905 pounds), and the House of Iron is the place to go if you're looking to bulk up.

Cloherty trained alongside Tiki Barber, who is trying to make an NFL comeback, as well as Jets running back LaDainian Tomlinson.

The hard work paid off. After playing at 245 pounds last season, Cloherty is up to 260 pounds. Cloherty said he's decidedly stronger this season, which has made him a better blocker. That attribute is especially valuable now that fellow tight end Nate Byham is out for the season with a knee injury.

Byham was the team's third tight end last season, mostly entering the game in short-yardage and goal-line situations.

Byham figured to have a bigger role this season in coach Jim Harbaugh's tight end-heavy offense. Byham was seeing plenty of work – and a lot of passes – before he was injured Sunday.

"It's stomach-wrenching to see Nate go down," Cloherty said. "And I feel so bad for him because he's put in so much work this offseason, was really having a great couple of days of camp. He was moving, he was blocking, he was doing it all. It's a big hole to fill. It's an opportunity that I really feel I can take advantage of."

Other under-the-radar players have stood out during the first few days of training camp:

• Offensive coordinator Greg Roman on Wednesday said all offensive players are doing a great job of learning a complex offense on the fly, especially the receivers. "The receivers have done as good a job at learning what we're doing as any group I've ever been around," he said. "That's a real credit to them."

Of the undrafted players, two receivers have stood out. Bridgewater's Tyler Beiler has shown impressive speed, while Monmouth's Chris Hogan, at 220 pounds, has been a handful for cornerbacks.

• Outside linebacker Kenny Rowe from Oregon (6-3, 232) doesn't jump out physically. But he always seems to be around the ball.

• Ex-Cal offensive lineman Donovan Edwards (6-5, 280) has been playing guard and has shown feistiness, even getting into a brief facemask-pulling standoff with outside linebacker Parys Haralson.

• Derek Hall played tackle for Stanford, but the 49ers have moved the 6-5, 307-pounder inside to guard.

• Nose tackle Ian Williams from Notre Dame has been getting plenty of work. With Isaac Sopoaga out with a hamstring injury, Williams has been the No. 2 nose tackle behind Ricky Jean Francois. Williams and Sealver Siliga from Utah have been getting much attention from defensive line coach Jim Tomsula.

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