One can debate all day whether it’s Tom Brady or his fleet of possession receivers who open up the middle of the field against one seemingly helpless opponent after another and never get to the real culprit. That’s because Mel Blount retired 35 years ago.

For all the well-deserved praise and suspect numbers Brady, Wes Welker, Danny Amendola, Julian Edelman and Rob Gronkowski have piled up slicing open defenses with shallow crosses, dig routes, three-step slants and seam routes, the truth is none of them opened up the middle the way the Pittsburgh Steelers’ Hall of Fame corner did in 1978, with an assist from Ty Law in 2004.

Those may well be the two most significant dates in the passing game since Oct. 25, 1906, which is the afternoon “Peggy” Parratt of the Massillon Tigers completed, fittingly, a short throw to Dan Policowski (playing under the assumed name Dan “Bullet” Riley for reasons lost in history). It seems right and just that the first thrown pass in pro football history was a form of what Bill Walsh called “the extended handoff,” meaning a short throw into what has become the wide-open plains in the middle of the field.

In recent years some have come to call this the dink-and-dunk offense. It’s hard to argue otherwise, but whatever you call it Brady runs the greatest one since the middle of the field was opened up like a can of sardines. Blame Blount and Law for that.

Andre Tippett can still hear former Patriots defensive coordinator Rod Rust’s gravelly voice reminding him and his linebacking teammates that one thing best not happen in the middle of the field in his day.

“When we were playing in the ’80s, if some joker tried running across the middle you put a hit on him,” the Hall of Fame ex-Patriots linebacker recalled during a discussion about how the middle of the field has changed. “Rod would say, ‘You better put a body on any (expletive) crossing the middle or I’ll put your body on the bench.’ You would mug guys in the middle, especially wide receivers.

“If they tried to pick you like they do today, you’d blow his ass up. They’d only run that pick once. You did not run a crossing route with somebody like Kenny Easley or Ronnie Lott or Steve Atwater at safety. If you came across the middle and Chuck Cecil was there, he would take you out.”

Cecil was a Pro Bowl safety with the Packers, Cardinals and Oilers known as “Scud” because he came in like a missile and blew up receivers who tried to cross the middle, often leading with his helmet. He once made the cover of Sports Illustrated under the headline “Is Chuck Cecil Too Vicious for the NFL?” If he was playing today, he would not be playing. He’d be suspended.

But that aspect of pro football has been radically changed in the past three decades. Today Brady and his receivers make a living running shallow crosses through the middle without the slightest fear of retribution. This wasn’t always how the game was played, as we were all reminded in the AFC Championship Game when Jacksonville strong safety Barry Church went old school on Gronkowski after he caught a pass in the middle. Church knocked him silly, dislodging the ball from his hands and synapses from his mind. That kind of hit was the norm until about 10 years ago, and one can see why it dissuaded quarterbacks from calling those plays and receivers from running them.

“I used to teach defenders to face the crossers and just eliminate them,” recalled former Bears linebacker coach Dave McGinnis, who was also a successful defensive coordinator during his over 30-year NFL coaching career. “You could eliminate the cross under five yards the Patriots run by stepping up and ‘Cujoing’ their asses. Today you cannot and that’s expanded the (passing) game horizontally. The anchor points of your defense have expanded. All you can do now is ask the defender to stay on a guy’s hip but even if he does it’s usually a completion.

“For most of the history of the game, if you tried to throw inside the hash marks you’d kill the receivers whether they had the ball or not. Clothesline ’em. Hit ’em in the head. Disrupt ’em. Let them know if they ran in there they were not going to run back out feeling very good. That’s what pass defense was. Today they’ve cleared the air space.”

The changes that Brady has feasted on for nearly 20 years are a reality based on safety issues and a desire that began in 1978 to add offense and limit defense. If that is the goal it has worked brilliantly in the latter case, allowing Brady and many of his peers to amass passing numbers like none seen before while slightly-built receivers like Amendola and Edelman make handsome livings in what used to be the most dangerous place in football.

In 1977, the average yards passing per game was 141.9 on 25 attempts, the final year of an era seen as the nadir of the passing game. Following that season the 10-yard chuck rule was reduced to 5 yards. It was known as the Mel Blount Rule because Blount was one of the most physical corners in a game then filled with them. If he got his hands on you, you were doomed.

And if safety Donnie Shell appeared to help out as you tried to cross the middle, you were concussed.

A year later, NFL offenses averaged 158.8 yards passing on 26.4 attempts, a more than 10 percent jump in passing production from the previous season. By 2017, the NFL average was 224.4 on 34.2 attempts, an increase in passing yards of 58 percent from the game played in 1977.

That change is not the sole reason the middle of the field is now as wide open as the Holland Tunnel. The second reason is the Ty Law Rule, an Indianapolis Colts-inspired “emphasis” from 2004 on firmly enforcing not only the 5-yard chuck rule but tightening restrictions on hand fighting and more firmly enforcing contact on receivers away from the ball.

What has resulted is the sight today of Patriots receivers wide open across the middle against defenses that can, frankly, no longer defend themselves.

Nate Burleson played 10 years in the NFL, beginning in 2003, the year before the Ty Law Rule was added. He caught 457 passes and was named to the Seahawks’ 35th anniversary team before moving on to analyst work on NFL Network. He recalled several years ago the difference between his early days in the NFL and today.

“I remember going across the middle my rookie year and thinking, ‘I’d better keep my head on a swivel because anybody can come and knock me off,’ ” Burleson said. “Nowadays, you can pretty much run around as much as you want, and a guy can’t put his hands on you past five yards.”

Talk of Fame Network asked Jerry Rice what he felt the impact of today’s game would be if he was still playing. The all-time leading receiver, who retired with 1,549 catches, said if he was playing now he’d have over 2,000.

“No doubt,” he said. “No question in my head.

“Oh my God!” Rice exclaimed. “With all the new rule changes? Back in the day even if the ball wasn’t coming my way I was still getting hit. They didn’t throw flags or anything like that. If I played with the rules today man I could have a field day . . . I played in an era I really loved but it was all about contact.”

The further you go back in history the more you hear voices like Lions Hall of Fame linebacker Joe Schmidt, who after retiring coached Detroit for six years (1967-72). The game he sees today is not one he enjoys.

“My opinion, which people may not like, but I think football is deteriorating,” Schmidt told me during a Talk of Fame interview. “You’re not permitted to touch the quarterback. He’s making $25 million. If I was making $25 million, they could hang me up and just hit me any time they wanted!

“The guys on the offensive line . . . all they do is push and shove each other. There are poor tacklers all over the place. Some kids can’t tackle, the secondary especially. Football, I think, was devised to physically outdo the other guy. I don’t necessarily think that’s the case now.”

Certainly it isn’t in the secondary. Former Patriots defensive coordinator Eric Mangini still recalls the hit linebacker Bryan Cox put on Colts receiver Jerome Pathon in Brady’s first start after the 2001 injury to Drew Bledsoe. At the time, Peyton Manning’s Colts were predicted to dismember New England, but the Patriots won 44-13 on a day when Brady completed only 56.5 percent of his throws. But that hit by Cox set a tone for the Patriots defense that resonated for years.

“That one hit changed the formations we got from Indianapolis dramatically,” Mangini recalled. “We were built to play in a phone booth. Once we established there would be a cost to coming inside, it was huge for us. You could gain something from the threat. How many chances do you want to take?”

For decades a hit like Church’s would have brought hosannas rather than calls of dirty play and intent to injure. Church’s intent was no different than Cox’s in 2001 — to bring down a guy who believed he could run unabated through the defense and do it hard. Church was flagged, which is standard today, but for decades those kind of hits were meant as a deterrent to what is now the norm — an indefensible game of pitch-and-catch where the quarterback knows the middle will be wide open not because of scheme but because of governmental fiat.

After the mandated “re-emphasis” with the Ty Law Rule in 2004, there was an immediate 10.5-yard per game average increase in passing yardage even though attempts went down slightly (31.9 from 32.2). That growth has continued almost unabated ever since, reaching the all-time high of 241.5 average passing yards per game in 2016 before sliding back to 224.4 this season.

To argue that today’s passers are more efficient than their predecessors is, on one level, statistically beyond argument. There is only one passer who played prior to 1977 (Hall of Famer Dan Fouts) in the top 65 quarterbacks in career average pass yardage per game. Johnny Unitas is 67th at 190.7. Do you really believe Drew Brees, the all-time leader at 282.9, is nearly a third better passer than Unitas?

Let’s leave the last word on that to someone who actually saw both in their prime. Upton Bell is a former Colts personnel director and Patriots general manager. He has high praise for Brees and feels Unitas and Brady are the two best quarterbacks in NFL history. But he also understands why the latter is torching defenses in record numbers.

“If you ran the routes they’re running today you would live to regret it,” Bell said. “The middle used to be no man’s land. Now it’s Disneyland.”