When I played with Tom Brady, he always told me the same thing: "You never want to see anybody else doing your job." 

It's not that he’s trying to make sure nobody else gets reps. It’s just the fact that he takes pride in his job, he loves what he does and he wants to be the guy out there doing it.

All that said, the ultimate reason why you go through practice is to get to Sunday. He's be playing for so long, he doesn't need as many practice reps because he’s done it a thousand times. 

He knows the playbook. He’s been with Josh McDaniels almost his entire career. So, allowing somebody else to get in there and take a few reps off your arm if you're dealing with an elbow injury is really important.

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What a lot of quarterbacks try to do is take reps during important practice periods like third down and red zone. You can increase your reps as the week goes on to get those situational football aspects into the playbook, because those are the things that really make the difference come Sunday.

The Patriots also have a "game plan" offense, so when there are new plays that go in for that week, you want to get those reps.

But if there’s a play you’ve run hundreds of times and you know it like the back of your hand, you might let the backup take that rep. I used to sub in for the running plays sometimes, and then the starter would come in for just the pass plays, just to get them.

 

Sometimes you have to protect a player against himself to make sure he's ready to go for Sunday.

For the Patriots' young wide receivers, it’s not so much about always getting reps with Tom. 

It's about practice execution -- getting the right depth on a route, for example -- regardless of who's playing quarterback. It's like Bill Belichick always says: "Practice execution becomes game reality."

Tom is super competitive, though. When I was a backup there, it was so few and far between that I got any reps with the offensive unit. Every rep counts during the week, and he's meticulous about details, so he wanted to be out there.

Sometimes you have to protect a player against himself in that case to make sure he's ready to go for Sunday.

During practice, there’s always great communication between the training staff, (Patriots head trainer) Jim Whelan, and Josh McDaniels and the rest of the coaching staff. 

Josh McDaniels and all the coaches decide before going out to practice: "OK, what specifically do we need reps on? What looks do you want to get?" And if it’s a run play that you’ve done 100 times, those are great plays to give the quarterback a little time off. 

If there are 10 plays in a particular team period, the starter might take six, and then they might let the backup get in there for four.

If the starter can do it and get through it, that’s the way they usually monitor that.

As far as Brady's elbow? It’s just something he'll work through.

He’s usually on the injury report with a shoulder, elbow or something like that. But when he gets into the game and his adrenaline gets going, I don’t see the elbow impacting him to an extent where he’s not able to make the throws he needs to make.

Editor's note: Matt Cassel had a 14-year NFL career that included four seasons with the New England Patriots (2005-2008). He's joining the NBC Sports Boston team for this season. You can find him on game days as part of our Pregame Live and Postgame Live coverage, as well as every week on Tom E. Curran’s Patriots Talk podcast and NBCSportsBoston.com.