Zone blocking can be a symphony of synchronized football or a disjointed mess that ends in too many drive-killing tackles for loss.

Vikings line coach and run-game coordinator Rick Dennison carries a healthy dose of it using the same schemes, techniques and teaching points first taught to him 25 years ago by Alex Gibbs, legendary line coach and godfather of the modern zone blocking.

The intricacies are many and minute. Here, for example, is a look at an outside zone run to the strong side:

• The quarterback must decide whether the front-side receiver can reach the safety to that side. If the answer is no, the quarterback changes the call.

• The tight end must widen the defensive end. If the defender sheds the block and charges inside, the play collapses.

• The five linemen must make identical steps and move in unison, blocking the next gap to the front side. If the gap is empty, go to the next level. “The first key,” says offensive tackle Rashod Hill, “is getting on your horse and everybody going fast in the same direction.”

• The tailback must be on a direct line behind the center. His first three steps must maintain that alignment, or the play is doomed. Hence the need for a fast center.

• The tailback must decide by his third step whether he’s bouncing outside or cutting back. His plant foot must be made by his fourth or fifth step. “They have what they call the ‘dot,’ ” coach Mike Zimmer said. “The dot is their read. They cut off the read.”

• Perfectly-timed cut blocks are essential. “A lot of times, that backside tackle responsible for cutting that three-technique [defensive tackle],” Hill said. “Not to give everything out, but people know that. … The tackle comes low and cuts him on that third or fourth step.”

• And, finally, the quarterback must sell the play-fake and naked bootleg to the weak side to freeze the backside end and prevent him from chasing down the play from behind. Making that sell is easier when the offense runs a fair amount of naked bootlegs.

“I like the scheme,” left tackle Riley Reiff said. “It’s playing faster. And if you’re playing fast, if it ain’t perfect, it’s still better than playing slow and not perfect.”

Dennison said the Vikings will “run all kinds of schemes, not just zone.” But when they go to the zone and it works, somewhere out in the desert the retired, 78-year-old Gibbs will be smiling.

“I hear he’s still walking up and down that mountain in Phoenix,” Dennison said. “My first time learning the zone scheme was back in 1995 [as Broncos offensive quality control coach]. Talking with Alex before practice, watching film with him after practice, getting to ask him questions about concepts … it really was a 24-hour information channel for me.”