One solution is to rush 4 but not the 4 down lineman. Dick Lebeau and Dom Capers both utilize 4 man pass rushes with a blitzer as the 4th rusher while dropping a lineman or rush linebacker into coverage. The following diagrams are examples from Lebeau’s 2002 Bengals playbook (pages 270-273).
Video of Capers’ Packers defense running this type of pressure is available here. These pressures increase the degree of difficulty for the offense by forcing the pass protection first to identify the 4 rushers and then get them blocked. Also these pressures can result in the best pass blockers (OL) blocking no one and the worst (RB) picking up the blitzer. This is especially advantageous when the blitzer is one of the defense's better pass rushers.
Most defenses have a bluff concept somewhere in their playbook where the defense fakes a blitz but instead rushes the 4 defensive linemen and plays normal zone coverage. Typically this involves the fake blitzers moving toward the LOS pre-snap and eventually bailing out to their actually responsibilities.
The goal is to convince the offense they are seeing a 5, 6, or 7 man rush and force them to react to that perceived pressure.
Offenses have many strategies to deal with the blitz. One plan offenses use is to throw 1 step fade to their best/tallest receiver. Because the offense is only taking a 1 step drop (catch & throw from the gun), getting pressure on the QB is almost impossible. The defense is most likely going to win the majority of these match-ups based solely on the low completion percentage of the play. Unfortunately, the offense will win some as well. A great leaper at WR, a bad height match-up (5’9 corner vs. 6’3 WR), pass interference, great throw & catch , or plain old luck can all lead to an explosion play. Teams seem to be getting better and better at completing this pass which means that the days of expecting the defense to win based on the offense’s inability to execute may be at an end. Additionally, as an offense attacks the corners the response is to loosen their coverage and the availability of slants, hitches, and fade-stops increases. By bluffing pressure the defense can get the offense to check into a 1 step fade and throw the ball up vs. a deep 1/3 corner. The Corner can play confidently against the fade because he knows he has help on shorter routes from the underneath droppers.
Another strategy offenses like to use is hot (sight adjust) routes to attack the blitz. The hot routes most commonly involve the interior or slot receivers adjusting their routes to replace where the blitzer came from. The bluff should force a hot route that will run into the underneath droppers.
A third pressure strategy is to align in or motion to tandem and bunch formations. Receivers then run pick routes to rub the man coverage and utilize fast crossers or flat routes as a built in hot concept. The defense is forced to become proficient at combo coverage or be willing to fight through picks. The possibility of a defender being picked creates the potential for an explosion play. Because the coverage is not man to man the pick routes lose their effectiveness and the crossing routes will be running directly into zone dropping defenders.
Offenses may also check to a max protection scheme and leave in an extra back or TE to add to the protection. Most defenses are not thrilled to see a 7 man pass protection when they are blitzing. However, in this situation the offense is allocating 7 blockers for only 4 rushers. While the pass rush may be blocked initially the coverage should be able to force the QB to hold the ball with 7 defenders vs. 3 receivers.
Another protection check is to slide the protection to or away from the pressure. Some offenses check the slide away from the rush when they see the NCAA blitz pre-snap.
The thought process is that the OT will follow the long stick inside and should then be able to pass the DE to the OG and be in position to pick up the inside blitzer. The running back has the blitzer off the edge. Teams that slide away from the protection can be attacked with Nickel Sting 8.
By bluffing the NCAA blitz the defense gets the offense to slide the protection thereby guaranteeing the blitzing Nickel is 1 on 1 with the back.
Other offenses check the protection to slide to the blitz.
The thought process being the slide can handle the blitz and the RB will not have to block anyone and will be free to check release. Teams that choose to slide to the blitz can be attacked with Nickel Tag 8.
Once the offense checks the protection to slide to the blitz the OT has to work through the DE to get out to the Nickel. The Nickel's speed should create problems for the tackle. The RB has to block a DE 1 on 1. By bluffing, the defense can dictate to the offense and create favorable pass rush match-ups.
Offenses that utilize the freeze tempo and check the sideline can be manipulated as well. The camouflage of the real blitzer(s) with the fake blitzer(s) will get the offensive coordinator on the sideline or in the press box to check the play to a blitz beater only to discover that there is no blitz. Check the sideline teams operate under a philosophy that the coach will read the defense and check the offense into an optimal call. Every time the offensive coordinator is wrong from the sideline it erodes his player's confidence in the game plan.
This concept is designed to complement cover zero and fire zone pressure. By coupling blitz and bluff you can create pressure both real and perceived. It is always nice to get something for nothing.