1-3-1 Baseline Out of Bounds Defense: Shape, Jobs, Traps

The 1-3-1 baseline out of bounds defense packs the paint and baits a deep lob. See the five jobs, the corner trap, the pass above the line and when to use it.

The 1-3-1 baseline out of bounds defense is a zone shape that packs the paint, makes the inbounder afraid to throw the entry pass and baits a lob toward half court, and this guide covers the five jobs, the corner trap, when to run it and where coaches split.

The 1-3-1 baseline out of bounds defense is a zone shape built only for dead-ball plays under the basket. It packs the paint, makes the inbounder afraid to throw an entry pass and baits a lob toward half court that can become a steal or a transition score. Any deep pass toward the backcourt counts as a win. The shape comes from the live 1-3-1 zone, and each of the five defenders has one job. This guide covers the shape, the jobs, the corner trap, the pass above the free-throw line, when to run it and where coaches split.

Five defenders, five jobs. Pack the paint, trap the corner and treat any long pass toward half court as a win.

The 1-3-1 Baseline Defense at a Glance

Question	Answer
What is the goal?	Pack the paint and make the inbounder afraid to enter the ball
What is the bait?	A lob toward half court
Who is on the ball?	X4, the longest or most athletic defender, with active hands
What is the trap trigger?	A pass into the ball-side corner
What does it protect?	The rim, the dive and the weak-side corner
Is it a base defense?	No. It is a change-up against a rehearsed set

Why Run a 1-3-1 on the Baseline

Most teams default to man-to-man on baseline plays because the offense is stationary and the matchups are clean. That works until a team has rehearsed a set that beats it. The 1-3-1 gives the offense something it has not practiced against. Instead of matching players, the defense fills the areas where the offense wants to catch the ball, and the inbounder has to throw into a formation built to pressure the pass. It pairs with another zone option, a 2-3 zone drop for the inbound that converts back to man afterward. See 1-3-1 Zone Defense for the live-ball version that this shape borrows from.

The goal is also a bait. Any deep pass toward half court is a win, since it turns into a steal or a transition score. Against a team with strong baseline sets, show the shape with the most athletic player on the ball and the lob as the bait.

1-3-1 baseline out of bounds defense diagram against a box set with one defender on the ball, two on the blocks, a ball-side wing and one inside the free-throw line

The shape. X4 is on the ball, X5 holds the ball-side block, X3 the weak-side block, X2 is the ball-side wing and X1 sits just inside the free-throw line.

The Five Jobs

X4 on the ball. The longest or most athletic defender, with active hands, going for a deflection on every inbounds pass. If the ball is entered to the ball-side corner, X4 and the ball-side wing trap it.
X5 on the ball-side block. Protects the rim from dives and post touches. Once the ball is in, he finds the nearest offensive player.
X2 on the ball-side wing. Closes out on passes to the ball-side corner. If nobody is in that corner, he can slide in to take away passes down the lane line.
X3 on the weak-side block. Takes weak-side dives to the basket and passes to the weak-side corner. If both threats show up together, he takes the dive first.
X1 just inside the free-throw line. Takes any pass entered above the line, slides lower if nobody is above it and takes the next pass out of a corner trap. In this shape X1 is the point guard.

These numbers belong to the baseline shape and do not always match the numbers in your half-court 1-3-1. Teach them as their own picture, and keep the jobs as standing assignments so any five players can rotate into them.

The Corner Trap

A pass into the ball-side corner is the trigger. X4 and X2 trap the receiver at once, with X5 staying on the block to protect the rim. X1 takes the next pass out of the trap. If nobody is in the corner, X2 stays free to slide down the lane line.

1-3-1 baseline out of bounds defense diagram with the ball passed to the ball-side corner and two defenders trapping it

Corner entry. The inbounder passes to 3 in the corner. X4 and X2 trap him while X5 stays on the block.

The Pass Above the Line

A pass to the elbow or the high post belongs to X1. He takes any entry above the free-throw line.

1-3-1 baseline out of bounds defense diagram with a pass entered above the free-throw line and the top defender taking the catch

Pass above the line. The inbounder hits 2 at the elbow and X1 takes the catch.

When to Use It

As a change-up. Keep man-to-man as the base and show the 1-3-1 against a team with strong baseline sets, so its rehearsed script meets a look it has not seen.
With your best athlete on the ball. X4 needs length and active hands to get deflections.

Every baseline defense works best with the basics in place. Match up, be set before the ball is live and protect the middle and the rim. See How to Defend Inbounds Plays for those rules and the other baseline options, including Box and 1 combinations.

Where Coaches Split on the 1-3-1 Baseline Defense

Zone on the inbound or not. A 2-3 zone drop and a full 1-3-1 shape are two zone answers. Another view warns that zoning a baseline situation automatically leaves you exposed to the screens and overloads that make up most inbounds plays. A compromise keeps man-to-man and gives the inbounder's defender a one-man zone in the paint.
What the inbounder's defender does. Here he pressures the ball with active hands. Other baseline systems have him sag for a three count and then smother, or play a one-man zone in the paint until the ball goes outside.
Switch or do not switch. Man-to-man systems split on switching inside screens. The 1-3-1 shape holds areas and does not chase players.

How to Practice It

Walk the five jobs with no offense. Every player says his job out loud.
Throw the three passes. Have the inbounder throw to the corner, above the line and to a diving cutter, and rep the response to each.
Practice the handoff from rim to man. Once the ball is in, X5 switches from protecting the rim to finding the nearest player.
Go live against the set you will face. Use the scout team to run the opponent's baseline script against the 1-3-1.

Coach Cheatsheet

X4 on the ball with active hands. Use your most athletic defender.
X5 and X3 own the blocks. X3 takes the dive before the corner.
X4 and X2 trap a pass to the ball-side corner.
X1 takes every pass above the line.
Any deep pass toward half court is a win.
Use it as a change-up and keep man-to-man as the base.

Questions Coaches Ask About the 1-3-1 Baseline Defense

What is a 1-3-1 baseline out of bounds defense?

It is a 1-3-1 zone shape used against baseline inbounds plays. It packs the paint, pressures the inbounder and baits a lob toward half court.

Who guards the inbounder in the 1-3-1?

X4, the longest or most athletic defender, with active hands, aiming for a deflection on every inbounds pass.

When does the defense trap?

When the ball is entered into the ball-side corner. X4 and the ball-side wing trap it.

Should the 1-3-1 be your base baseline defense?

Most teams default to man-to-man. The 1-3-1 works as a change-up against a team with strong rehearsed baseline sets.

What is the biggest weakness?

A zone has to adjust to a ball behind the basket and can be exposed by screens and overloads, so drill the dive and corner responses until they are automatic.

All of these pages sit under the Special Situations hub. Related guides include How to Defend Baseline Out of Bounds, Basketball Baseline Out of Bounds Plays, Types of Defense in Basketball and 2-3 Zone Defense.

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More Coaching Guides

Back to How to Defend Inbounds Plays and every Special Situations page.