New rules for defensive backs are no laughing matter for coaches Raheem Morris (left) and Jay Gruden.  (John McDonnell/The Washington Post)

Washington’s head coach and rookie class won’t be the only new twists to keep an eye on when the Redskins take on the New England Patriots in the teams’ preseason opener at FedEx Field Thursday. During the offseason, the NFL passed a clutch of new rules and vowed to put greater emphasis on a few existing ones.

As a pre-game warm-up, we offer a primer on eight changes and clampdowns — and one limited experiment — that might come into play tonight:
● Tighter policing of illegal contact between defenses and wide receivers. And it has been giving defensive-back coaches fits all preseason. The specifics: When the quarterback in in the pocket with the ball, defenders can’t initiate contact with a receiver more than five yards from the line of scrimmage.

● Total prohibition of hands-to-the-face. In the past, such contact had to be “prolonged” or snap an opponent’s head back to draw a whistle. This season, any hand to the face incurs a 10-yard penalty. Similarly, “jersey pulls” will be policed more strictly as holding.

● The definition of clipping has been expanded. Blockers can no longer roll up on the side of defenders’ legs. Before, only the backs of the legs were safeguarded.

● The clock will keep running after sacks during the final two minutes of halves. In the past, it was stopped until the ball was spotted.

● Taunting and abusive language directed at players or officials gets zero tolerance. The penalty: 15-yard unsportsmanlike conduct.

● Celebrations won’t be as celebratory. Players can spike the football after touchdowns. But their teams will pay for any theatrics that involve using the goal post “as props”—such as dunking the ball.

● Though it sounds as if it’ll drag out the already drawn-out replay system, the NFL insists it’ll expedite it. We’ll see, now that the on-field referee can phone the league’s vice president of officiating, Dean Blandino, in New York as a “lifeline,” of sorts, for consultation on controversial replays.

● For clarity’s sake, the field-goal uprights have been extended from 30 to 35 feet above the cross bar. It’s viewed as a response to a controversial Baltimore field goal that sailed directly above an upright, depending on vantage point, in a 31-30 Ravens victory over the Patriots in 2012.

And finally, the experiment: In an effort to inject more drama into the extra point, the ball will be moved back from the 2-yard line to the 15, resulting in the equivalent of a 33-yard field goal. NFL kickers connected on 99.6 percent of extra-point attempts last season. If this change spices things up over the first two pre-season games, when the experiment ends, the league may make longer extra-points the rule in the future.