---

FOXBORO - There are four quarterbacks in the Patriots' training camp.

One is a future member of the Pro Football Hall of Fame, so it's a pretty good bet that Bill Belichick knows what he can do.

The other three, however, are fairly close together on the depth chart - and that poses a specific problem to Belichick as he begins the game-action phase of his evaluation of his roster.

The Patriots' coach said Tuesday that he has yet to determine the appropriation of playing time for his signal-callers in Thursday night's preseason opener against the Baltimore Ravens at Gillette Stadium (7:30 p.m.; Ch. 5, 64). There probably won't be much of a demand upon Tom Brady's time, although even future Hall of Famers need to blow the rust off every now and then. But the quandary facing Belichick is how much time to give to Matt Cassel, Matt Gutierrez and Kevin O'Connell.

Cassel, entering his fourth year, is more of a known quantity. Gutierrez had a strong camp last year and won his job because of it, but he needs to show progress in game situations. And O'Connell may be a raw rookie, but he's not some unknown, undrafted free agent from the hinterlands. He's a third-round draft pick, and that's too high of an investment to cut or relegate to the practice squad, where he could be lost to any team willing to make an offer. Quarterbacks are unique in the evaluation process, Belichick said, because they can't be evaluated for anything other than just one position.

"It's no different than a specialist, like a kicker or punter," he said. "There's only so many punts in practice. There's only so many snaps in practice. And if you're trying to evaluate two or three people, then how do you break that up? How do you do that fairly, or how do you do it to get the best evaluation?

"I don't think there's any right or wrong formula," he added. "You just do what you think is best."

There has been speculation that because of O'Connell's high draft position, the Patriots may be inclined to keep four quarterbacks on the roster as they did in 2000, when Brady was a rookie. But Belichick is not known as an individual who'll keep anyone on the roster without documentable proof of his value to the team - which is why O'Connell was spied on the field later than everyone else at a recent practice, going over his throwing mechanics with Brady.

"This is the time of year when everybody works on their specialty," Belichick said. "These guys threw in the spring camps, but it's not like the throwing we're doing out here. They take that time to work on specific throws, specific routes and the volume of throwing."

O'Connell's main area of focus has been taking the ball from under center and dropping back, as he spent much of his time at San Diego State playing in the shotgun formation.

"There's probably a lot of things he hasn't done in a while, or done very much of at all," Belichick said. "And he's worked hard on those."

As the helmet turns

The ongoing soap opera over the Patriots' use of in-helmet radio receivers for defensive players reached a climactic moment Tuesday when Belichick admitted he would not utilize the technological advance in the game against the Ravens.

Reporters, already sensing Belichick's disdain for the topic, waited until the end of Tuesday's press conference to ask about the helmet headsets. "We won't use it during the game," Belichick said, semi-lightheartedly. "Is that what you're looking for? Put that in the headlines, then. No, we won't use it."

His tone grew a little sterner when a reporter asked in follow-up if it was his intention to go over the procedure with the team at some point in the preseason.

"We'll do what's best for the football team," he said. "That's all I can say. I wouldn't make any promises of what we will and won't do. We'll just do what we think is best."

It's beginning to appear that, given Belichick's frequent substitutions on defense and his apparent disdain for the rule that was passed in part because of last year's "Spygate" controversy, the Patriots may never use the radio-equipped helmets on defense and continue to manually signal in plays from the sideline. Stay tuned

Quick kicks

Good news on the linebacking front: Veteran Mike Vrabel was activated off the physically-unable-to-perform list for Tuesday afternoon's practice. Still no word why Vrabel missed the first 12 days of practice ...

Amid suggestions by reporters that Brady has practiced less in this training camp than in the past, Belichick disagreed. "I don't think it's been that much different than it was last year," he said Belichick called Tuesday a "transitional" day of training camp, in which the focus begins changing from teaching and installation into preparation for the preseason games and, ultimately, for the regular season. Coincidentally, it was also the last day for the "Patriots Experience" theme park for youthful visitors to training camp The team will have just a walkthrough today in preparation for the game against the Ravens, then will be off until Monday, when there are two practices scheduled, one in the morning open to fans, and an evening session inside Gillette, open only to the media.