When the 1977 baseball season is discussed now and in time to be, those who care for the game will smile. This was the year, they will sigh, the hitters returned from exile.

Never in the history of the game has there been a season in which batting averages, run production and the frequency of home runs were all so high.

To be sure, during the Lively Ball Era from 1920 to 1939, the major league's composite batting averages were higher every season than this season's standard of 8.98 runs a game.

And seven times during The Home Run Craze from 1955 to 1962 there were more round trippers than this season's average of 1.77 clouts per game.

But never have all three - average, runs and homers - been so plentiful at the same season.

When this first season of the spunky new Rawlings ball is remembered, it will be thought of as a year of excess. This season promises to usher in an unprecedented era. All the games vital forces - hitting, pitching, slugging and speed - are in near-perfect balance for the first time.

Every baseball connoisseur knows that each season provides a practically unique vintage of the sport.

Fans mention 1968, the year of Too Much Pitching (major league ERA 29.8) with a shudder, the way they might a cheap Ripple. They recall 1961, The Year of Home Run (1.9 per game) with excitement, but a sense of reproach, a champagne hangover . . . too much of a good thing.

By contrast, this season is already as popular as a heartly burgundy, with major league attendance up 17 per cent and 75 hitters above .290.

Although Minnesotan Rod Carew's near .400 batting average has gotten most attention, his feats are only a bit more singular than those of a half-dozen others in the summer of burgeoning batting.

The major leagues, without a 45-homer hero since 1971, nor a 45-homer hitter since 1973; currently have four men ahead of a 45 pace, with three others on schedule for 40. Mike Schmidt's 26 homers put him on time for an even 50.

No hitterhas had 130 RBI since 1971. Now five are ahead of that pace, with both George Foster and Steve Garvey threatening to become the second man since 1949 to drive in 150 runs.

For whatever category a fan has a penchant - .400 average, 50 homers, 150 RBI, 20 triples (Carew), 240 hits (Carew), 50 doubles (several) - at least one man is in plausible pursuit.

If team goals are the Dan's taste, Boston is ahead of the 1961 Yankee record of 240 homers in a season.

In another part of the forest, the Cincinnati Reds, deep in second place, are emulsifying the individual marks of 1976 that made their regular lineup The Great Eight.

Let one projection after 81 games speak for each Red: Pete Rose (1.22 runs), Ken Griffey (.338), Joe Morgan (130 runs), George Foster (152RBI), John Bench (40 homers), Dan Driessen (112 RBI), Dave Concepcion (.302), Cesar Geronimo (.285).

Many will denounce this season's batting barrage as the gimick result of a joke Rabbit Ball.

But when this season is put in a long historical perspective, it appears that the game's vital statistics - batting and slugging average, homers and steals per game, ERA - are at almost Golden Mean levels.

The Lords of Baseball have been trying to fine-tube the sport's numerical indicators since they bellixed it 17 yeas ago with the first expansion. They finally seem to have it right, temporarily.

Baseball historians have long seen the postwar period (1947-1960) as the game's Periclean Age. Hitting and pitching were in proper balance with nine runs a game the norm and a collective batting average in the high .250s to low .260s the healthy range.

This season the American League is averaging 9.01 runs a game (up from 8.02 in '76) and the National 8.95 (up from 7.96).

The hardest thing to understand about 1977 is how so many healthy offensive statistics can coexist with that equitable average of 8.98 runs a game.

The current .267 major league average is the highest since 1940. The current 1.77-per-game home run pace would be the eighth-highest in history.

And this year's average of slightly under 1.40 steals per game is one of the three highest since 1919.

Whatever the reasons - good relief pitchers choking off rallies, improved control allowing slightly fewer walks - baseballs can be thankful it has escaped the chaotic 1960-1976 period.Perhaps it will become known as baseball's Roller Coaster Age.

First, expansion to 10 teams, plus a newly introduced lively ball, resulted in too many homers in 1961-62, so the strike zone was drastically shrunk in 1963.

The result? By 1968, .300 hitter were as rare as wildbeasts at 14th and F streets, so the smaller strike zone was reinstated and the mound chopped down.

Hitting revived temporarily in 1969-70, almost to the levels of this season, but by 1972 the American League was in such offensive doldrums (.239 league average. Detroit wins division flag with team total of 17 steals, that the artificial offensive resuscitation of the hitter was rushed into existence.

For a time fans can look on their game and call it good. If an occasional routine fly hall seems to take a hip-pity-hop in midflight and land in the carrot patch beyond the fence, it is the price the game must pay so that a mere 3-0 lead does not seem insurmountable.

If stolen bases are down nearly a third this season, it is the inevitable concomitant of the more cautious beginning strategy that always accompanies home runs. Nonetheless, nine players are ahead of a 50-theft pace.

Only the pitching profession sheds tears, seeing its collective ERA soar from 3.51 last year to 4.02 this year. The pitchers' union will simply have to recognize that hitting is the game's good red wine.

And, few will dispute that 1977 has been an extremely good year.