The definition of a motion offense is a play or set that can be run over and over without having to reset anything.  Maybe the most well known motion offense is the Flex.  The Flex offense has been around for ages, and one of the main reason why it sticks around is because despite it being so simple, the play is really hard to stop.  Everyone in the NBA knows when it is coming, but teams still run it anyway (and they are successful with it – some more than others).

Not only does the defense have to deal with a set that basically has all five offensive players moving at once, but there are a number of different options that the offense can take advantage of.  If the defense doesn’t have their head on a swivel or they don’t communicate well, they aren’t going to be able to stop the Flex.  Here is the standard Flex:

1. The play starts with the point guard choosing a side to dribble on (in this case, he chooses the right side).  When he does choose a side, the big men on the opposite block (the power forward here) pops to the elbow.  The point guard hits him with a pass.
2. The center now sets a screen for the small forward who flashes along the baseline, looking for the basketball.  He can either cut to the block or look for a quick seal in the middle.
3. As this is happening, the point guard sets a down screen for the center.  The center uses this screen immediately after the small forward uses his screen.  After setting the screen the point guard clears out to the corner to establish proper spacing/floor balance.
4. If the power forward can’t hit the small forward flashing along the baseline, he swings it out to the center who is now flashing to the opposite elbow.
5. We now have the same action that happened the right side taking place on the left side.
6. As all of this takes place, the offense keeps its shape the whole way through.  You can basically run this over and over as many times as you please.

Here is the basic flex set in action:

Here, the Bulls get through one elbow to elbow sequence before they are able to enter the ball into Luol Deng.  Deng uses the screen to get his defender on his back and quickly seals in the paint.  Taj Gibson enters the ball and Luol Deng is able to draw the foul (and almost get the three point play).

Here is another look at the basic flex, and this clip really shows what kind of confusion an offense with everyone moving creates.  All the ball goes from the left side of the court to the right side, the Bulls continue going through the motion here.  Eventually Kirk Hinrich and Gilbert Arenas run into each, freeing up Keith Bogans to pop out to the three point line (instead of the elbow) and knock down the three.

Now that we have the basic Flex offense down, we can get into some variations and other options.

If you notice in the first clip, Julian Wright (the man covering Luol Deng) is a little hesitant cheating behind the screen to beat Deng to the spot.  This is why.  This option is a quick little change of direction by the small forward.  Instead of going baseline, the small forward notices his defender cheating under the screen and quickly flashes to the high post.  The point guard who is supposed to set the down screen for the center now ends up setting a double screen for the small forward.  The beauty of this is if nothing comes of the this cut, the center just goes to the opposite block (as the point guard still goes through his motions) and the flex still keeps its shape.

Here are two separate videos of this option in real time:

Here, Raja Bell flashes up to the high post instead of using the screen and cutting along the baseline.  The reason is he notices his man getting caught in the middle of the lane cheating to the baseline.  Now, nothing comes of this play, but you can see the Flex reads here.

Again we see the option.  Here, Gordon Hayward decides that he does not want to go baseline.  He makes a similar cut that Raja Bell does, but instead of flashing to the elbow, he curls to the opposite block and gets the ball with his defender on his back.

Another option that you can run out of the flex set is setting it up for an ISO at the top of the key.  Here it is in real time:

Now obviously this doesn’t look like your original Flex set.  However, you do see some of the Flex offense principles.  Once the ball gets entered into the elbow, instead of setting a down screen, the point guard clears out.  Bargnani gets a downscreen, and you now have an ISO for him.  Because the defense needs to stay with all of the motion, you have them all spread out with Bargnani at the top of the key.  Eventually he is able to draw the foul.

This next option is another read off of the defense. In the above clip, Kobe sinks in the lane to help out on the cut to the baseline.  Reacting to that, Raja Bell quickly pops out to the wing where he can knock down an easy uncontested jumper.

The final option we are going to look at today again forces the defense to spread the court, and uses that to their advantage.  Here, the Hawks run through the standard flex motion a few times through, every defender needs to stay with their respective man, and that spreads out the court, leaving a lot of space on the block.  That’s when Al Horford decides to turn and post.  Once he catches the ball, there is no double because the defense is all spread out.  Horford turns, faces, and knocks down the jumper from the elbow.

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We have looked at four options working off the Flex offense (not counting your base set), and we aren’t even starting to scratch the surface.  That is what makes the Flex so hard to stop.  If the defense does one thing, the offense react off of that and do something that gets them open.  In addition to all of these options, there is a number of different ways you can get into the Flex (for example in the first Jazz clip featured they enter the ball into the corner, look for a post up, it isn’t there so they get into the Flex).

Another thing that makes the Flex offense so awesome is that different teams run it different ways.  The Bulls and the Jazz seem to run the Flex in your standard way, taking the time to set screens (and setting up screens) correctly .  The Atlanta Hawks on the other hand seem to skip the standard screens and set rub screens as they run through their cuts.  This is another reason why the flex is so hard to stop, there is no one set way to run it, so you can’t really prepare for it unless you are doing so on a game by game basis.  That’s tough for coaches and defenses.