After eight seasons of running West Coast schemes, Vikings players are learning a more wide-open offensive system with roots that stretch back to both the early days of Air Coryell and the heyday of John Robinson’s power-running Southern California Trojans.

Offensive coordinator Norv Turner, whose 40th season as a coach will be his first with the Vikings, was a player at Oregon when Robinson was an assistant there. Turner then followed Robinson to USC and the Los Angeles Rams.

As for the passing game, Turner isn’t a direct disciple of Don Coryell’s famous route-numbering system, although he did observe Coryell’s San Diego training camp practices as a guest of former college teammate and then-Chargers quarterback Dan Fouts. Turner picked up the system in full when Ernie Zampese, one of Coryell’s prized pupils, joined the Rams in 1987.

“When I left the Rams in 1991 to go to Dallas as offensive coordinator, I took what I thought was the best part of our running game and the best part of the passing game that Ernie brought,” said Turner, who helped the Cowboys win two Super Bowls in three seasons. “But I think I’ve added something to the system every year based on the coaches I’ve been with and the players I’ve had.”

Rather than identifying routes and plays by name, Coryell’s three-digit system was based on a numbered route tree that was intended to help players visualize a concept and excel more quickly.

“Once you conceptualize it, it becomes easier,” quarterback Matt Cassel said. “You just can’t see the numbers, whether a 6 is an in-cut. You have to be able to conceptualize that ‘Seam 678’ means something and be able to see that whole picture in your mind.”

Running back Adrian Peterson compared the team’s early practices with Turner to “performing open heart surgery without a license.” But as training camp opens this week, players say the learning process is progressing well, not only because of extra practice time but also because Turner has spent 30 years compiling film cutups of players executing the same plays the Vikings are working on now.

There’s also an obvious trust factor based on Turner’s track record. Besides the two Super Bowl rings, Turner’s offenses have produced three top-five scoring attacks since 2007, five league rushing champions — Emmitt Smith (1991 to 1993), Ricky Williams (2002) and LaDainian Tomlinson (2007) — and two receiving champions — Michael Irvin (1991) and Josh Gordon (2013).

“It takes time, but it also helps when there are cutups of a Jay Novacek running an ‘Odd 9’ and catching a touchdown in the Super Bowl,” Vikings tight end Kyle Rudolph said. “Or a Michael Irvin running the ‘Bang 8.’ Norv has been doing this longer than I’ve been alive, so you know it works. You can visualize it just by watching all these past players run the same exact play in a Super Bowl that we’re working on in an OTA in May.”