Aside from the games themselves, training camp is the best proving ground in the NFL.

It's when players who look dynamite running mini-camp drills in shorts can be exposed for their shortcomings. It's also when relative unknowns who have remained under the radar can begin to emerge and find their place on the team.

Longshots do make it every once in a while. Like last year, when the Packers had two non-drafted rookies in linebacker Roy Manning and offensive lineman Chris White earn spots on the 53-man roster by the end of camp. Manning went on to play in 15 games in 2005, while White was activated for one as well.

Who might be the sleepers of training camp in 2006? There's no telling for sure, but here are five guys to keep an eye on as things unfold:

Atari Bigby, safety

There's a glut of defensive backs competing for roster spots, but Bigby is one of the outsiders who improved his chances in the offseason with a strong performance in NFL Europe.

Playing free safety for the Amsterdam Admirals, Bigby led the team in tackles with 61 (43 solo), defended four passes and added five solo tackles on special teams. That experience should give the coaching staff a more polished, instinctive player to evaluate than the one who was signed to the practice squad last November and activated for just one game.

"I think his confidence level will pick up to where he's going to get out here and know he can play," said Reggie McKenzie, Packers Director of Pro Personnel. "I think he already knew he could play, but when you get out there and play and do it, you gain more confidence, and he did. His speed and his size and his toughness, that was always there.

"To be free safety over there in Europe, he was kind of like the team captain, communicating with the guys."

Noah Herron, running back

Of the players listed here, Herron by far has garnered the most attention.

Signed off the Pittsburgh Steelers' practice squad on Nov. 30, 2005, Herron played in the Packers' final five games last year, rushing 45 times for 121 yards and two touchdowns, one each against the Bears and Seahawks to close the season.

Herron was quickly noticed for "his ability to pick up the system," McKenzie said.

"He's a smart player, he's an instinctive runner, and he catches the ball very well. People want to hammer him because he's not a blazing speed guy, but he's fast enough. The guy can run."

Herron carried that momentum from a strong finish into the offseason and made a strong impression during mini-camps and OTAs while backfield mates Ahman Green and Najeh Davenport were still recovering from injuries.

"He always showed confidence, that part wasn't an issue," McKenzie said. "One issue was his decisiveness and burst. When he makes a decision it seems like he's ready to burst through the hole now. That improved as far as he's concerned."

Josh Bourke, offensive tackle

A non-drafted free agent from Grand Valley State in Allendale, Mich., Bourke was a Division II AP All-America first-team selection last year after missing the 2004 season with a knee injury.

Thus far, Bourke made an impression with his athletic ability for such a big guy (6-foot-7, 314 pounds), a quality that's needed up front in the Packers' new zone-blocking scheme.

"He understands angles and leverage, and for a tall, 6-7 guy, he can bend," McKenzie said. "He can play both left and right tackle, he has the ability to move, to block speed and block power. He's what you look for in a tackle, and it seems like he's got some toughness about him."

Bourke will have to put that toughness on display with the pads as a pro on for the first time.

"It was only a quick look we got in minicamps and OTAs, but he didn't disappoint, that's for sure," McKenzie said.

Tory Humphrey, tight end

Another player who improved his stock in NFL Europe, Humphrey was Amsterdam's fourth-leading receiver with 19 catches for 206 yards (10.8 avg.) and a touchdown. In studying the film from overseas, McKenzie said Humphrey's blocking ability stood out.

"He has good speed, really good hands, he has the total package of a complete tight end," McKenzie said. "All he needed was some playing time so he could get his confidence level up."

Humphrey's biggest challenge will be cracking the Packers' solid top three at tight end, with Bubba Franks, David Martin and Donald Lee seemingly entrenched in their spots.

"Any other time you could kind of pencil him in, but right now he's going to have to compete like the dickens to get on (the final roster), and I don't believe for one minute he won't do it," McKenzie said. "Because he will compete, and I think he's going to make it hard on those coaches."

A.J. Cooper, fullback

A non-drafted free agent from North Dakota State, Cooper was a tight end in college making the switch to fullback in the pros. At 6-foot-1 and 240 pounds, he looked the part in mini-camps and OTAs, and with so many question marks about the overall health of the running backs, there's no telling how things will shake out.

"He's got good size and really good hands as a fullback, and it seems like he understands the game," McKenzie said. "It's hard to get a true judge of those guys, the fullback and linebacker-type guys, until they get the pads on. That's where we have to make sure, can he block, and we don't know that yet."