Calvin Johnson said he had a “fair share” of concussions although he was never officially diagnosed with one (AP)

There was a good reason Detroit Lions receiver Calvin Johnson retired at age 30, not that we couldn’t have figured it out months ago.

Johnson detailed some of his injury history to ESPN’s “E:60,” and discussed the things he had to do to stay on the field during his nine NFL seasons. The most startling revelation was that he believes he and other NFL players suffer a concussion as frequently as “every third play.” What makes that so scary is Johnson was never officially diagnosed with a concussion in his career.

“Concussions happen,” Johnson said. “If not on every play, then they happen like every other, every third play, you know. With all the helmet contact, guys hitting the ground, heads hitting ground. It’s simply when your brain touches your skull from the movement or the inertia, man. It’s simple to get a concussion, you know. I don’t know how many I’ve had over my career, you know, but I’ve definitely had my fair share.”

Johnson said he was concerned about the concussion issue before he retired. There were other parts of the interview that should cause concern, like Johnson talking about painkillers early in his career and saying “the team doctors and trainers they were giving them out like candy.”

The culture isn’t close to changing. There have been fixes, such as better player safety rules and a better understanding of concussions. But there will always be the fundamental challenge of players feeling a need to play through pain — whether they feel that pressure because they want to compete or because they’re worried about losing their job in a world of mostly non-guaranteed contracts — and of teams pressuring their star players like Johnson to play even if they’re banged up. It’s hard to imagine a time when that won’t be the case.

“The team doctor, the team trainers, they work for the team. And I love ’em, you know,” Johnson said in the “E:60” interview. “They’re some good people, you know. They want to see you do good. But at the same time, they work for the team, you know. They’re trying to do whatever they can to get you back on the field and make your team look good.”

Players are smarter about some of the dangers they face in their sport. Some, like former Baltimore Ravens offensive tackle Eugene Monroe, have been outspoken about issues like painkiller use (and it’s fair to assume teams probably don’t love when players become self aware). But there’s no way to get rid of the violence in the sport, and players are still willing to engage in behavior that is a severe risk to their long-term health just to play every Sunday. That will never be eliminated.

Johnson understood what he was putting his body through to play football, and he got out after nine seasons while he was still a top NFL receiver. He won’t be the last to step away at an early age, either.

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Frank Schwab is the editor of Shutdown Corner on Yahoo Sports. Have a tip? Email him at shutdown.corner@yahoo.com or follow him on Twitter!

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