You've seen 3-4 and 4-3 defenses. Buddy Ryan made the 46 famous. You've heard of the 5-2, the Wide Nine and the goal-line jumbo. There are endless ways to arrange the 11 men charged with stopping the opposing offense.

On Sunday, the 2017 Pro Bowl might contain the first known instance of the "7-4" defense. At the very least, the NFC squad will have practiced this inverted formation.

READ: BUCS WELL-REPRESENTED IN SKILLS CHALLENGE

Well, "practice" might be a bit strong of a term. On one rather fun snap during the NFC's Friday morning practice, the front four and the back seven suddenly decided to switch. Maybe it was intended to confuse Drew Brees and the NFC offense; more likely, it was just another opportunity for the league's all-stars to blow off some steam and have a little fun, which they rarely get to do on the practice field.

"Why not have fun?" asked Tampa Bay Buccaneers defensive tackle Gerald McCoy, who is preparing for his fifth straight Pro Bowl. "Usually at practice you're really game-planning, so you can't do all this stuff. Like, one time, all the DBs and linebackers ran up and all the linemen dropped out. So we switched spots."

One of McCoy's Buccaneer wide receiver Mike Evans, was on the other side of that exchange, and he was just as happy to get a laugh as to run another serious route. Evans is in his first Pro Bowl but it didn't take him long to figure out that all-star practices are a bit more … relaxed … than in-season workouts.

"We're balancing good – about 97% having fun, the other three percent being serious," said Evans. "We'll see [on Sunday] – I think it's going to be an explosive, high-powered game. But they say it might be raining, so that will make it even more fun."

A normal NFL practice alternates between different types of drills, some of which include the entire team and some of which are split into different position groups. For instance, there are the so-called "7-on-7" drills that focus on the passing attack and don't include the offensive and defensive linemen. There is a lot of this type of work at the Pro Bowl because the banging in the trenches isn't as severe in the all-star game.

READ: BUCKY BROOKS' FIRST-ROUND MOCK DRAFT

The NFC defensive linemen spent a lot of time this week in the far end zone, either working on drills with Cowboys (and former Buccaneers) coach Rod Marinelli or messing around with each other to kill time. A typical sequence on Friday typified this balance between fun and serious preparation. For a while, McCoy and such DL teammates as Everson Griffen, Cliff Avril and Michael Bennett took turns running fade routes into the back of the end zone. Then Marinelli joined them and they engaged in a very energetic set of drills testing their "get-off" speed and how quickly they could change direction.

Things got a little more serious at that point, if still very good-natured. McCoy drew a round of praise from his teammates for a particularly quick and sharp cut to his left after one particular get-off.

"It got intense because we were trying to see who really had the get-offs and who had the best feet and change-of-direction," said McCoy. "It's still competition. Ultimately the goal is to beat the AFC and get this check, but while we're here, the only way to get there and make that happen is to compete in practice."