Defensive coaches always say you can never have enough pass-rushers.

This season will test that theory more than any year I can remember. More quarterbacks are working with fast-tempo offenses filled with quick throws and some read-option plays. More teams have question marks with some of their top pass-rushers either because of surgeries or scheme changes.

Look at the New York Giants. People thought they were overdoing it in 2010 when they drafted Jason Pierre-Paul to a roster that had Justin Tuck, Osi Umenyiora and Mathias Kiwanuka. Now Tom Coughlin has worries because Pierre-Paul's back surgery makes him a question mark for the opener and Umenyiora left for Atlanta.

The Seattle Seahawks added two pass-rushers who combined for 18½ sacks last season -- Cliff Avril and Michael Bennett. All of a sudden that overload looks thin. Defensive end Chris Clemons, who had 11½ sacks, is coming off a knee reconstruction. Although Pete Carroll says Clemons is ahead of schedule, there is no guarantee he will be ready for the opener. Bruce Irvin, last year's first-round pick who led all rookies with eight sacks, is suspended for the first four games.

The Giants have collected talented pass-rushers such as Jason Pierre-Paul (90) and Mathias Kiwanuka. Kirby Lee/USA TODAY Sports

The New Orleans Saints, Philadelphia Eagles and Buffalo Bills are some of the teams switching from 4-3 to 3-4 schemes, and they will have to see how quickly their pass rushes can adjust against fast-paced offenses. It won't be easy.

The New England Patriots started the move to fast-paced offenses last year by having coaches spend time with former Oregon coach Chip Kelly, who is now with the Eagles. Tom Brady went to the no-huddle last year and snapped the ball quickly. The Pats averaged 74.4 plays a game, including one game against the Denver Broncos in which they ran 89 plays.

More teams are trying to speed things up. Peyton Manning is quickening the pace in Denver. At Tuesday's San Diego Chargers practice, media members counted Philip Rivers and other Chargers quarterbacks getting off more than 160 plays in about 85 minutes, including several in which Rivers had three-step drops.

Those high-tempo offenses can be nightmares to defend. Defensive coordinators count on their best pass-rushers to pressure or sack the quarterback. Against these fast-paced, no-huddle offenses, ends can tire out after five plays, making coaches think about substitution.

"As everyone knows, there is an importance getting to the quarterback and affecting the quarterback," Seahawks defensive coordinator Dan Quinn said. "You need to get the quarterback off his spot."

Quinn is in an interesting position. He was Carroll's defensive line coach two years ago on a young team that had only one pass-rusher, Clemons. The University of Florida hired Quinn last year to be its defensive coordinator, giving him a chance to call plays against spread offenses that run plays at break-neck speeds.

"I remember when I first saw the Auburn tape and how they were playing at a fast pace," Quinn said. "Games are so much longer in college. Against fast-pace offenses, the clock is always stopping. You look up four hours later and say, 'Is this done yet?'"

Fast-paced offenses create physical and mental strain on players and coaches. Players have to worry about fatigue. Coaches have to make sure the pass-rushers have enough energy left in the fourth quarter to get to the quarterback.

"You need to have a larger rotation of guys if you play the fast-pace offenses in order to be able to finish games in the fourth quarter," Quinn said. "In college, you have more players so you try to rotate more in during those games"

Quinn is preparing for everything. Clemons isn't ready for practice, and Quinn is using Irvin at defensive end and outside linebacker so he'll have position versatility when he returns in Week 5. Avril is practicing despite a plantar fascia foot problem. Bennett will need shoulder surgery after the season but is going to practice and play.

Quinn also has had linebackers Malcolm Smith and Mike Morgan put their hands on the ground and rush from the defensive end spot.

"We are cross-training guys to play a variety of roles," Quinn said. "It's not as if we are moving guys to new positions, but we are trying to get as many guys into a variety of roles when we need them. We have to be prepared."

Other teams have to be prepared for anything. The read option caught some teams unprepared to deal with it last year. Coaches have spent the offseason working on that. They also have to get ready for quick offenses, putting a rush on finding new ways to rush the quarterback.