|Take It On Purpose|
1) Holding in pile ups. If I were coaching a defensive team that was facing a tempo offense, I'd take lessons from baseball, where the hitter asks for time, or the base runners try to draw throws to first. So loose footballs get kicked aside, guys get tackled through the whistle and for a couple of second beyond, and my secondary guys get in the way of wideouts as they try to get back to the line. If everybody does it on every play, it's going to be very hard for the refs to call it constantly.
2) Timeouts on defense. If your offense is scoring in 3 to 4 minute drives, how badly do you really need to hang on to your timeouts... and isn't it better to use them to make sure you've got rested and ready personnel on that third down play that might actually get the unit off the field? You are going to see this, along with de facto defensive timeouts for iffy replay challenges.
3) Home field advantage. How quickly does the chain gang really need to move, especially when the home team is trying to keep the defense from being gassed? How about replacement balls, or mysterious TV timeouts? Oh, dear, the clock seems to be malfunctioning. Guess the refs are going to have to fix that. Shame it happened just when the home team defense was looking really gassed. Oh, and there's been reports of lightning in the area. Everybody take a knee!
4) Scrubs ride carts. Let's say you are a defensive coordinator. Your team is gassed, and your team is just about to punt. Any chance that you might go to Player #45, a ham and egg plugger who runs down the middle of the field, and tell him to execute That Special Play \, where he crumples to the ground against a 2-man wedge as soon as he sees the PR signal for a fair catch? Suddenly you've got five free minutes of oxygen and peace, and he gets to make that little reassuring wave after making sure not to flinch for a few minutes. Winners ride carts!
5) Conversations. Football is a verbal game, right? So perhaps your defensive players need to talk to the refs more. And their hothead opponents. Perhaps challenging the spot of the the ball, or saving some really off-color remark, joke, or non sequitur. That's the reason Richard Sherman is such a good CB for Seattle, right?
6) Intentional offsides -- but only where the entire defensive line goes early, preventing that free play problem. What's worse -- five yards on a second and one that cedes the nearly automatic first down, or getting lit up when your gassed CB gets torched? I'm taking the five, myself...
Add any that I may have missed in the comments...