FOXBOROUGH -- It’s a simple, three-word phrase that is the overarching theme to everything that Patriots coach Bill Belichick preaches: Do your job.

But when it comes to rookies, the philosophy doesn’t always take the first time around. And when a first-year player doesn’t do his job, he’ll oftentimes try and make up for an error by trying to do his job … as well as the job of a teammate on the following play in an attempt to try and impress the coaches. And that rarely ends well.

With roster spots on the line in Friday night’s preseason game against the Redskins, look for an overeager youngster to follow up a bad play with an even worse one that was borne out of an attempt to please the coaching staff. With younger players, when mistakes come, they come in pairs -- a missed tackle leads to blown coverage, a bad block will set the stage for a negative play.

“It’s happened to a lot of us,” veteran safety James Sanders said Wednesday afternoon, referencing a 2006 game against the Broncos that quickly went from bad to worse for the defensive back when he piled mistake on top of mistake because he was too busy thinking about the first error he made.

Sanders motioned to teammate and fellow safety Brandon Meriweather a few lockers down.

“Brandon, it’s happened to him,” he said. “I definitely told Pat [Chung] it’s happened to me. Even Randy [Moss] has said a couple times when he was younger, ‘It happened to me.’

“You can make the game become a lot worse by trying to do too much.”

“Trying to do too much” can sound like a good thing, but on a team that preaches the philosophy of team defense above all else, it can cause a series of breakdowns. If one player overcommits and another has to leave his own area to cover for his mistake, that creates an opening in the defense. Someone tries to cover that exposed area, and that leaves another problem.

“That’s the learning experience -- you can’t try and do too much. You just have to play your game and relax,” Sanders said. “You can’t let that get to you.”

Traditionally, most defensive breakdowns of this nature have occurred because of an overeager defensive back looking to make up for a previous error. But thanks to the lessons preached by Sanders, Chung, who will be playing in the third preseason game of his short NFL career Friday night in Washington, knows that a successful defensive back has a short memory. If you get beat on one play, don’t dwell on the miscue. Shake it off and move on.

“You mess up as a rookie, you try and make a play on the next play, and try and do too much, it could backfire,” Chung said. “You just have to learn to keep your composure, relax and just go on to the next play.

“When you’re a DB, you have to have a short memory. If you get beat on one play, that play is over. Go get a hit on the next play. If you don’t get that play out of your mind, it can mess up your whole game. You just have to have a real short memory, and go out and play the game.”

It’s not just the rookies and other youngsters who could misfire -- players new to the system who might be fighting for a roster spot also know the danger of trying to do too much. Alex Smith is locked in a pitched battle at the tight end position, one that will likely end with a veteran getting released. However, he knows that by following Belichick’s three-word philosophy, his chances of making the team will increase.

“I never think you should try and do too much. Just do what’s asked of you. When you’re number is called, make a play,” Smith said. “That’s when mistakes happen -- when you try to do more than what’s expected of you and what you are capable of doing. So my goal is just do things when my number is called.”