How to Improve Your Basketball Team’s Defense With the Shell Drill

• By Grant Young

Even if a basketball team has an elite array of offensive weapons at their disposal, no squad can expect to consistently win if they don’t have a solid defensive foundation. 

And defense can be tough to teach players; especially at the game’s higher levels, where most teams are reliant on man coverage in order to slow down opposing offenses.

Hence why drills are a great way to instill defensive strategies and philosophies within a defense. And Brandon Bailey has the perfect drill that any coach can use for their own team’s benefit. 

Coach Brandon Bailey is currently the head men’s basketball coach at DePaul University. Prior to that, Coach Bailey was an assistant coach at Ohio State University and an assistant coach for the Boston Celtics, who recently won the 2023-24 NBA Championship.

After beginning his career as a video intern with the Celtics in 2011, Coach Bailey rose through the Celtics’ coaching ranks to ultimately earn himself an assistant coaching position. And the defensive that he has sworn by throughout this ascension is called the Shell Drill. 

In his ‘Shell Drill To Stimulate Your Defense’ course, Coach Bailey details the best ways you can utilize this drill to turn your defensive unit from a liability to one of your team’s strongest assets. 

3 on 3 Shell - RIM Protection

In a 3 on 3 version of the shell drill, Coach Bailey wants to start by positioning his three offensive players in the drill: one player in one of the corners, another player at the perimeter on the wing (who starts with the ball), and a third player on the other wing opposite him. 

Once his offensive players are placed into these three positions, he will place three defenders guarding them, all of whom are a few feet away in a natural defensive position.

Coach Bailey’s goal is to create/simulate scenarios and reads that his players will have to deal with in the game. One example of this has to do with rim protection. Specifically, Coach Bailey wants his players to get reads on when to inch out and guard a player along the perimeter compared to when his players should remain closer to the paint, to assist with rim protection. 

So the drill would start with the player who’s holding the ball passing it to the other wing. That player would then attack the point. If they succeed and make it past their defender, the player defending the offensive player at the corner then must decide whether to stop that player’s drive or remain on their player in the corner. 

Coach Bailey stresses that, as soon as this help side defender can see that the guy driving’s shoulders are past their initial defender, he will need to abandon his player in the corner to stop an easy layup.

But if the initial defender manages to stay in front of the guy driving, then the help side defender should remain close enough to their guy in the corner so that they don’t have an easy shot.

The 3 on 3 shell drill is perfect for practicing these scenarios because the court isn’t congested, and guys can see the consequences of their reads. 

Square Shell

A second version of the shell drill that Coach Bailey swears by is what he calls the square shell. 

This drill involved positioning four offensive players: one in the corner, a forward or center along the baseline, a third player along the perimeter on the wind (who has the ball), and a fourth along the opposite wing. 

The key to this drill for defenders is to be communicating about the pick and roll. When the drill is running, the big along the baseline will be able to choose between setting a pick and roll for the player with the ball or setting a back screen for the player in the corner. Regardless of who the big decided to screen for, communication between the three defenders on that side of the court will be crucial.

And if the defenders manage to stop the initial pick and roll action in the drill, the ball should get swung over to the fourth player on the opposite wing. This will force the defense to adjust while play is still underway. 

One of the other guards in this drill can also set an initial screen, rather than the big. But the most important part is that the initial on-ball defender does not know where the first screen will come from so the defenders behind him must be communicating at all times. 

Kick Out Read

The focus for this third rendition of the shell drill is to get bigs to kick guys out while in the post. 

This drill will require four defenders and four offensive players. But the entire defensive action relies on the big defender, who will likely be somewhere in the post. 

Once the drill starts with pick and roll action at the top of the key, the big defender will need to make a read on whatever happens. If their teammates on defense switch to a matchup that’s more favorable for the offense (say, if a guard gets caught on an opposing team’s big), then the big defender will need to orchestrate a switch once that big offensive player tries to maneuver into the post. 

The main goal of the shell drill is to facilitate communication between defenders and get the game-like repetitions that these defenders might face in a game. Your players receiving these reps in practice could spell the difference between winning and losing in games.