Explaining the Pick and Roll Defense Ice

Also called downing it or bluing it, Ice is one of the most prevalent defensive strategies in the NBA today.  You see it used scores of times on a nightly basis, but probably just think of it as normal at this point.  Ice is used on the side pick and roll to prevent penetration into the lane.
The idea is to not let the opposing ball handler actually use the screen.  If the ball handler can't use the screen, space isn't created, rotations aren't forced, and there isn't penetration.  We're going to use one Clippers play as an example.

Willie Green gets the ball on the wing and calls a big man over for a screen.  As the Blake Griffin lumbers over, his man, Boris Diaw, will call out to "ice" or "blue".  The man defending the ball handler (Tony Parker) gets on Green's lane-side hip which won't allow Green to attack the screen and create space.  Boris Diaw drops down to the baseline and zones off the lane.  Some aggressive teams (like Miami) will actually trap the ball handler here, but most teams just create a little pocket with the ball handler between two defenders and two sidelines.
At this point the ball handler has four options (Not including the a pass to the shooter in the opposite corner or wing who will almost always be open.  The number of players that can make this pass can be counted on one two hands). The ball handler can drive baseline and take an ugly floater/fade away shot that very often hits nothing but the top of the backboard.  While there is a 5% chance the player will make some crazy over the basket tear drop, it's an incredibly inefficient shot to take.  The second and most utilized option is the pocket pass.

This is most commonly a bounce pass between the two walling off defenders to the big man who pops to the elbow.  This is where the defense has to start to rotate and you can already see Kawhi Leonard and Tim Duncan flashing over.  All the defense has to do is rotate quickly enough to not give up the elbow jumper until Boris Diaw can recover, although some defenses will trap the big man at the elbow.
 
The third option is for the weakside big man (DeAndre Jordan) to cut baseline and establish position for an entry pass. This can be so effective because in most cases the weakside big man's defender (Tim Duncan) will be focused on helping should the ball handler make a pocket pass (and in the shot above you can see this).  With one hard cut, deep position can be established.  At this point all the player needs to do is a little dropstep and make a layup.
The final and least used option is a cut from the weakside man on the wing to the strongside of the basket.  This is often a tough pass to make and an even tougher layup to finish; the player will be getting the ball running at full speed with his body faced away from the basket.  It's a nearly impossible play to make which explains its rarity, but you will see some players do this from time to time. 
With defenses using this strategy more and more, offensive are going to have to adapt.  The NBA is just a big game of cat and mouse between offensive and defensive strategies.  We went from the ultra fast Showtime of the 80s to the thug 90s.  The early 2000s were ruled by slow teams like the Spurs and Pistons.  The last part of the decade shifted to play embodied by those explosive games between the offensive juggernauts Mavs and Suns.  Who knows where we are going to go next.