FOXBORO — Now entering his third season in the NFL, Brian Hoyer is getting used to playing the game of football in his head.

Hoyer knows that what may look boring to some from a distance – the walk-throughs and casual appearance of practice without pads – is the lifeblood to his career, which includes completions on 26-of-42 passes for 264 yards and a TD over 10 NFL games, all in relief of Tom Brady.

Hoyer needs to stay sharp and mentally focused for any situation and circumstance that may arise in a game.

Remember the lesson Bill Belichick taught him in the season finale against the Texans on Jan. 3, 2010?

Brady played most of the game despite the Pats having already clinched their playoff spot. Belichick called on Hoyer late in the second quarter and on the Patriots’ last drive of the game, trailing 34-27.

“We didn’t really have anything set,” Belichick said at the time. “We just went out and played. We let him play a couple of times, maybe those are good situations that are going to come up for him. We played the game like we thought we needed to play it.”

The Patriots lost the game but Hoyer gained valuable experience that only game experience can teach.

And sometimes, when you’re the back-up QB taking reps with the second unit, the only way you can stay sharp is by watching what the first until does in practice and think through, ‘What would I do on that play?’

“You have to take a lot of mental reps,” Hoyer said. “There’s obviously not as many practices as we usually have in training camp so it’s a lot of more mental reps that you’re trying to get and whenever you get in there, you try to take the most advantage you can.

“I think with any extra year you have, there’s more comfort level but there’s always a lot of room to grow. With the limited amount of reps you have now, you really have to go out here and think about every play, even if you’re not the quarterback in there. You have to call the play in your mind and go through it just the way you would.”

And clearly, the challenge is bigger this year with training camp jammed into a shorter summer window.

“Obviously, there’s fewer practices,” said Hoyer. “It’s hard to tell. We just try to come out here and get better with the reps we do have and work harder every day and be better than we were the day before.”

This is where the things most fans don’t see become bigger and bigger in terms of helping the team and back-up quarterback get ready for 2011.

“It’s huge,” Hoyer said. “The film work, the meetings, the walk-throughs, those are crucial. Last year, you didn’t always have the walk-throughs, you would just come out and practice. You have to treat the walk-throughs like they are a practice. Even though it’s literally a walking pace, you have to go through it like it’s a real practice.”

That approach is what Hoyer hopes will keep him ahead of rookie quarterback Ryan Mallett, who has shown off a gun of an arm in practice but still needs to learn the intricacies of one of the most complex offenses in football, something Hoyer has on him by two years.

“I think just attention to detail,” he said. “You have to pay attention to little things and the things that are important like third-down, the situational football, which is huge when it comes to games. I think when you practice it in practice and it becomes game reality. You just have to come out here and execute like it is a game, whether it’s third-down, red area, goal line, all that stuff, it’s what’s going to happen in a game so you want to be able to practice it.

“Being the back-up quarterback, you have to be ready to go at any point, whatever may happen you have to be ready to go. I try to treat practice like that. Obviously, I’m not always taking the first reps but when I get thrown in there, I’m just assuming I’m getting thrown in in the middle of a game so you have to carry on from where you’re at and what you have.”

On Thursday, Hoyer figures to get a lot of playing time after Tom Brady comes out after the first one or two series of the preseason opener against the Jaguars at Gillette.

“I think they’re always significant, especially for guys like me where this is your one guarantee in the year that you’re going to be in there playing so I take them like they’re real games and I’m looking forward to Thursday night,” said Hoyer.