Adrian Peterson had an $18 million salary “scheduled” for 2017 on his last contract with Minnesota , but the franchise’s all-time leading rusher was never realistically going to get that money from the Vikings given his age and position.

Russell Okung had the potential for $48 million and four more seasons on his self-negotiated deal with the Denver Broncos, but the 29-year-old left tackle never saw it. He became a free agent and signed with the San Diego Chargers.

Remember that $78 million contract Donovan McNabb got from the Washington Redskins in 2010, during the twilight stage of his career? About $70 million evaporated into that NFL netherworld of nonguaranteed money, after the six-time Pro Bowl pick was unceremoniously released by the Vikings the following season.

Such is the financial reality for players in this $14 billion enterprise, with a steadily rising salary cap that’s at $167 million this year. The maximum value of most NFL contracts simply won’t be paid out, unlike for their peers in professional baseball, basketball and hockey.

According to NFL Players Association calculations, signing bonuses and other guaranteed compensation accounted for a little more than 60 percent of all payments to players last year.

“When you think about what we do for our organizations, the injuries and the pounding that we take, you would think that there would be more appreciation for your players,” Peterson said in an interview with The Associated Press this week after practice with the New Orleans Saints. “It’s just so unfortunate when you think about the physicality and the toll that football takes on your body.”

NFL players are usually most riled up about this in early July, when they’re in vacation mode and NBA free agency begins with big-money deals for relatively unknown reserves. Just glance at some of their Twitter accounts, and the…