One can only imagine the depths of Chuck Fusina's frustration. With just seconds left in the U.S. Football League's championship game Sunday night, Fusina's Philadelphia Stars trailed the Michigan Panthers, 24-14. He dropped back to pass, searched for a receiver and found a melee.

Amidst the approximately 2,000 fans who swarmed the field at Mile High Stadium, Fusina passed for a two-yard score to a former Philadelphia Eagle, Rodney Parker. The touchdown meant nothing and Parker discarded the ball the way one might toss aside an empty beer can.

Beer was what lubricated the mob scene to follow. After a long delay, the Stars ended the scoring and the league's first season with a two-point conversion pass. That was followed by a celebration that seemed to last as long as the four-hour game.

With police under instructions to defend the goal posts, fans threw everything from beer bottles to half-eaten sandwiches at them. Twenty-five people were arrested for disturbance violations. The police, approximately 200 of them, had to resort to billy clubs and mace to quell the crowd and clear the sod.

USFL Commissioner Chet Simmons, who said he would gladly have paid for a pair of goal posts had he known they would be the ostensible source of so much trouble, has made it clear that the league intends to endure. Before game time, Memphis became the league's 18th city. The franchise was awarded to Arkansas businessman Logan Young. The league had already announced five other new franchises for the 1984 season--Houston, Jacksonville, San Antonio, Tulsa and Pittsburgh.

Slowly, the league is making an impression on the sports-viewing public. A number of important events were crucial to that arrival: the television contracts with ABC and ESPN; the signings of outstanding rookies such as Anthony Carter, Kelvin Bryant, Tim Spencer and, especially, Herschel Walker; the distinct improvement in the quality of play in the second half of the season.

Simmons concedes that such rapid expansion will dilute the quality of play somewhat. He insists, however, that with the proper scouting, the league will be able to build strong, competitive teams that will one day be on a par with those in the NFL. Expansion into larger cities is intended to raise the USFL's national television ratings; teams in smaller cities like Jacksonville are meant to capitalize on being "the only show in town," according to the commissioner.

Simmons said the league would continue to compete against the NFL for top-flight college players. Asked about reports that the new league would pursue Marcus Dupree, Oklahoma's sophomore tailback, Simmons said he expected that someone will soon challenge the rules preventing the drafting of undergraduates--a rule ignored when the New Jersey Generals signed Walker in late February.

Even if many of the league's teams continue to be way below NFL level, the playoffs may prove the best advertisement. The two divisional playoffs and the championship game, played before 50,906 fans, displayed solid, exciting teams--teams that had been assembled just six months ago. And standout individuals.

Take Bobby Hebert's play Sunday night. Hebert, a rookie quarterback from Northwest Louisiana, developed into an exciting passer as soon as he gained about a month of professional experience and became acquainted with his best receivers. Hebert was named the title game's most valuable player. Carter caught nine of his passes, for 179 yards.

Hebert played the championship game under a death threat. The Rocky Mountain News received a phone call saying he would die "by high-powerd rifle." The Denver police's SWAT team attended the game as a security precaution.

All that, and game pressure, too.

But Hebert completed 20 of 39 passes for 314 yards and three touchdowns. The first two were caught by Derek Holloway and gave the Panthers a 17-3 lead in the third quarter. Philadelphia rallied in the final period with a 26-yard field goal by David Trout and a 21-yard touchdown pass from Fusina to Willie Collier, plus a two-point conversion.

With three minutes left, the Panthers led, 17-14, and needed insurance. With the ball on the Stars' 48, Hebert came to the line, having called a pass play designed for Holloway.

Hebert, however, saw a blitz formation developing on Carter's side of the field. He changed his call, went back to pass and threw to Carter with ease for the winning score.

It was an NFL play in any league.