Pro football of the 1980s began in 1978, with two major rules changes designed to light up the scoreboards.

Wide receivers suddenly were able to get off the line of scrimmage without being chopped down by linebackers. Defensive backs were no longer permitted to bounce the receivers about the secondary. And pass protection, as practiced by the offensive linemen, became legalized holding.

The new rules were clear: thou shalt not touch the pass receiver, but it's all right to strangle a defensive end or tackle with his own jersey if he's trying to sack a passer. The quarterback also was afforded increased protection from the officials' quicker whistle. An average of 40 points was scored in an NFL contest last season, an increase of 9.4 percent over 1978 and a 17 percent increase over 1977. One hundred and four more touchdowns were scored last season than in '78, 67 more by passing and 37 more by rushing.

For the purist, these changes are regrettable. But for the fans, the NFL's front office, and the media, the result has been delightful. Quality of play often is measured, in the minds of most observers, by the number of points recorded during 60 minutes of action. That being the case, welcome to the greatest decade in the history of the game -- and bring along a calculator to add up the score.

Entering the 80s, a passer throwing for 300 yards a game -- once considered a Unitas-like feat -- has become an almost weekly occurrence. Eleven quarterbacks topped 3,000 yards in 1979. The reason was obvious: every passer has more time to throw, to spot the secondary receiver; and every receiver had more time to execute patterns to break open short or deep.

The fear factor has been lessened considerably at the offense's skill positions. Given new courage, many journeymen passers have "blossomed" or "matured" into outstanding performers. There is, after all, no substitute for pressuring the passer. Now, because of the rule changes, the only high-percentage way to get to the passer is with an all-out, high-risk blitz which, if unsuccessful, may backfire disastrously.

The result of these changes, along with the longer 16-game "parity" schedule which penalizes the more successful teams, has been to bring better balance to the league. Obviously, it is much easier to play sandlot ball than the complex defenses designed by Tom Landry, Chuck Noll or George Allen.

But Noll, to his everlasting credit, was the first of the big-league thinkers to realize just how dramatically the new rules would affect the game. Noll had the Steelers ready at the start of the 1978 season for the transformation which was bound to happen. By late '79, all the premier coaches knew the differences. By the middle of last season, even the dummies were forced to acknowledge that the game had undergone a forced revolution.

This season, all the coaches will be opening up some offense from the start. Few leads will be safe. The game threatens to follow the new Minnesota formula adopted by former conservative Bud Grant: allow one TD to score two.

Vince Lombardi would never appreciate what has happened. It is not the game he coached. It is Don Coryell's game -- explosive, Dan Fouts throwing for a record 4,082 yards -- and let the assistants worry about coordinating the defense.

Two years ago, in my first column of the season, I bemoaned the rules changes. "Pete Rozelle never asked my permission," I wrote, knowing that the game played throughout the early and mid-70s would never return once the public was treated to a taste of the easy TD.

But there is no going back. A handicapper or a bettor must adjust to these changes as well as the players and coaches.

The last two seasons of "Playing Football" have been winning ones, although hardly in the tradition of the column's first four years. Form has taken such a beating that betting "the (under) dog at home" is all a novice has needed to know in order to compile a record against the spread far superior to any professional handicapper.

Keep the faith. I am .646 since starting this column in 1974, with never a losing season, having picked 217 games correctly against the line while losing 172, and, all importantly, earning a net profit (mythical, naturally) of $29,029, including $810 last season.

The odds are still the same, risking $11 to win $10. As long as there is no change in the way this game is played, I'll win.

You can bet on it.