Much has been made of the theory that Chris Evert's mind has been more on her upcoming wedding than on her tennis in recent weeks, and after her startling elimination from the $275,000 Avon Championships tonight, there can be little doubt that this is true.

As in her 6-3, 6-1 humiliation by 16-year-old Tracy Austin Thursday night, Evert seemed far away from the sport she has dominated for five years as she was whipped tonight by Dianne Fromholtz, 6-2, 6-3.

Moving listlessly, making unforced errors in painful clusters, and displaying a totally uncharacteristic mental lethargy, Evert never boke Fromholtz's serve and never came close to getting into the match.

Afterward, the 24-year-old Evert -- who will marry English tennis player John Lloyd in Fort Lauderdale, Fla., on April 17 -- declined to attend a postmatch press conference for perhaps the first time in her career.

Explaining that she was too upset to face the press, Evert instead issued a terse statement through a high school friend of hers who is now the traveling press officer for the Avon tennis circuit.

"I don't feel the media has been sensitive enough to my personal situation," the rather poignant statement said. "I searched for my competitive fires, but they weren't there. I promise you (that) this summer I'll be tough and eager."

After her honeymoon, Evert plans to resume competition in three European tournaments on clay this spring.She has not lost a match on clay since August, 1973.

Fromholtz, an improving 22-year-old Australian left-hander who won the last "regular-scason" tournament of the women's winter circuit at Boston last week, thus gained the semifinals of this eight-woman playoff after losing on opening night to Virginia Wade.

She finished the double-eimination preliminary portion with a 2-1 record, and will play Austin (2-0) in one semifinal Saturday.

In the other semi, Wimbledon Champion Martina Navratilova (2-0) will play Sue Barker (2-1), who overcame fellow Englishwoman Virginia Wade tonight, 5-7, 7-5, 6-2.

In addition to Evert and Wade, Greer Stevens and Wendy Turnbull were eliminated. Saturday's winners will meet, with a $100,000 top prize at stake, Sunday afternoon.

The Barker-Wade match was a tedious, streaky, 2 1/2-hour affair that twisted and turned on great flocks of forehand winners and errors by Barker, who has returned to her 1977 form after a dismal season last year.

Wade played defensively, repeatedly pushing her backhand, and was even more erratic than Barker. She led 5-4 in the second set, and got to 40-30 on Barker's serve, but could come no closer.

Barker, who broke her engagement to Australian player Syd Ball last fall, relied on the advice of her Longtime coach, Arthur Roberts, who told her at the start of the year to run around her backhand and hit her potent forehand as often as possible as in her better days. "If you have a battleship, don't shoot corks," was his counsel, and his 22-year-old protege has heeded it to full advantage.

The crowd of 11,825 at Madison Square Garden expected to see Evert come out like great guns against Fromholtz after her embarrassment by Austin the previous evening, but it was not to be.

Evert struggled after leading 40-0 in the first game of the match, and held serve only after four deuces and three break points against her. That was foreshadowing of many woes to come.

Fromholtz played confidently from the start and grew tougher as she saw Evert floundering. She moved well, attacking the ball from the backcourt, hitting through her vastly-improved backhand and repeatedly whacking cross-court forehands for glorious winners.

Evert, who got only 59 percent of her first serves in the court, was not as erratic off the ground as against Austin, when she committed an astonoshing 52 unforced errors. But she was still terribly sloppy, and on the defensive throughout.

Evert only rarely changed up the pace on which Fromholtz was feasting, and curiously kept hitting to the forehand that was hammering so many angled winners past her. Her timing was off -- she was late on shots time and again -- and her usually faultless court coverage and footwork were again suspect.

Evert seemed caught up in a vortex of self-destruction. After losing her serve in the third and fifth games of the first set, she all but sealed her doom by dropping 11 straight points from 1-1 in the second, 10 of them on unforced errors.

At that point, the crowed tried to rouse Evert with bursts of sympathetic applause and encouragement. How ironic it seemed that the cool world-beater who has had audiences cheering against her for years should suddenly become a gallery favorite out of pity. But even the will of the people could not revive her.

Last year, Evert lost only three of 59 matches she played. So far this year, she is 23-6, and has lost three in the las three weeks.

Singnificantly, all six of her defeats in 1978 -- two by Navratilova, one each by Stevens, Barker, Austin and Fromholtz -- have been in straight sets. She simply seems preoccupied with her pending nuptials, unable to produce the surges of mental toughness on which her superiority is so dependent.

"I know that Chris really hasn't got her mind on the game right now. I can't blame her for feeling that way. I know what she's going through," said Fromholtz, who slumped last year during her engagement, since broken off.

"... It's very difficult to concentrate, especially with the wedding coming up so soon. I wouldn't even try to play tennies.

"But I think everybody treats Chris with a great deal of respect, because she's a good person, she doesn't run anybody down, she always has something nine to say about you when she beats your brains out.

"All of the women respect Chris. We all understand her situation. I think that when she does get settled into being a married woman, she'll be back in there making us all chew our fingernails again."