One of the major reasons the spread offense took off in college football was the zone read play. When teams realized that they could unleash the power of the option and feature athletes at QB with such a simple play that required only a slight tweak to the already ubiquitous inside zone concept, things really took off.
Rich Rodriguez started ripping teams with this scheme and it really took off when Vince Young's Longhorns made it the foundation of their offense in 2004 and 2005 seasons that ended with back to back Rose Bowl victories, the latter of which brought Texas a national championship.
Teams across the nation installed the play as everyone realized that it didn't take a particularly athletic QB to really punish defenses by pulling the ball and taking the edge if the unblocked defensive end were to crash inside trying to make the tackle on the running back.
By leaving the backside end unblocked teams could get an extra double team on zone and, unless the backside safety was Troy Polamalu, playing their defensive end aggressively against the running back was going to help even slower QBs sleepwalk to five yard gains.
So naturally, defenses responded and now have multiple techniques for defending the play which are dulling the impact of the scheme around the college football world. This is why you hear Urban Meyer noting, "we aren't really a spread-option team anymore," because things are evolving. Here's why:
Counter #1: The scrape exchange
The scrape exchange basically tries to get numbers to the real point of attack with the zone read play, which isn't really the double teams but the read-side of the play. The DE crashes after the RB like he normally would, but the read-side linebacker (W in this instance) gets wide to take the QB if he keeps it.
The problems with the scrape exchange came up pretty quickly, one of which is that on a zone read play like we have diagrammed above the offense could run it as an outside zone play with the RB aiming wide from the outset of the play. Can the DE be realistically expected to make the tackle, even unblocked, when the RB is running wide to the other side of the formation? Some can and some can't. If he can't, the defense is now outnumbered to the strong side.
Another problem comes when teams respond by using an H-back or fullback instead of a tight end. With an H-back on the field the offense can bring some variety and keep the defense guessing on whether he's going to trap block the unblocked end for the benefit of the RB or else arc around and take out the scraping linebacker as a lead blocker for the QB. If the DE and LB become hesitant they can become sitting ducks.
Counter #2: Drop a safety
Aggressive teams will often just drop the backside safety so that the QB has no time to get going and no angles to exploit when he pulls the ball down. This is a better solution for offenses that are feature a great athlete at QB who may or may not be a strong passer.
It's less of a good idea against teams that have a dangerous receiver lined up to the read-side (Z in this instance) and a competent passing QB that can deliver the ball to him down the field. The defense is left to guess when it's safe to drop the safety down without getting burned by some variety of vertical route on a play-action pass.
Of course if a team has a great cornerback that can lockdown the receiver without help then the offense is in a tough spot.
Counter #3: Attack the mesh point
With this tactic the defensive end steps inside to replace the offensive tackle and eliminate a cutback lane while moving upfield towards the QB and RB with his shoulders square to the line of scrimmage. This eliminates running angles for both the QB and the RB and can drastically reduce the effectiveness of the play.
For the running back, he can no longer dive inside into the space between the end and the offensive tackle and punish the cutback lane. For the QB, it forces him to turn laterally to have any hope of winning the edge. If the defensive end is a particularly good athlete (and patient about when he dives after the RB or QB) then the QB may not be able to get past him at all. Even if the QB is quick enough to get wide, the end can take away the best angles and allow team pursuit to reach the play.
This is probably the soundest way to combat the play, but against the better running QBs who are experts at executing this play it requires a defensive end that is both a very good and very disciplined athlete. Otherwise, the defensive scheme can get them in a heap of trouble if the QB quickly wins the edge because there won't be another defender with primary responsibility to stop him.
Another trick offenses are using is to run the "mid-line" zone read, where they leave a defensive tackle unblocked instead of a defensive end. The tackle is generally less athletic and less experienced on how to perform this strategy effectively, as Tennessee demonstrated against Oklahoma in their contest the other weekend.
Counter #4: Blitz!
There are tons and tons of blitzes like this that teams love to use for attacking the zone read. It works in principle much like the scrape exchange in that it's looking to fool the QB into keeping the ball only to get destroyed by the blitzer. If the QB notices the blitz and hands off to the RB, the defense is often weighting the blitz to attack the zone scheme by stunting the DL away from the read-side and/or dropping defenders there to make the play.
If the RB here would have to immediately run wide or else be dropped for a loss by the unblocked defensive end peeling after him, but when he got wide he'd find that the defense had slanted all their numbers there and now outnumber the blockers.
This is arguably the best way to attack the zone read play, especially if the QB is an inexperienced athlete that hasn't yet learned all the possible chess moves that the offense can utilize to combat this kind of aggression. While having the end slow-play the zone read is often effective, this way of approaching it can yield disasters for the offense such as tackles for loss or fumbles.
Countering this approach requires giving the QB another option to the read-side, such as a quick pass outside or some other variety of pitch-option that can allow him to get the ball into space quickly and discourage blitzing.
The days of offenses using the zone read as a quick and easy way to use the QB as a runner to punish defenses for aggressively attacking zone runs are gone. Teams that hope to rely on the play as an every week strategy now need to have multiple ways to run and protect the play because defenses have caught up.