Perhaps the most trenchant critique of the quality of play in the U.S. Football league so far has come not from some grizzled National Football League coach or owner but rather from David Letterman, the only slightly athletic host of NBC's "Late Night."

One night Letterman decided to establish a "USFL Hall of Fame" and displayed a few "exhibits" on the air.

First, he fanned out a bunch of bubblegum cards and said he had the cards of every star player in the league. The camera zoomed in on a half-dozen photos of Herschel Walker. Then Letterman touted a book entitled "The Story of the USFL"--which of course opened to blank pages. A "record book" was filled with pitiful midget-league statistics.

The USFL is now in its 14th weekend and any highlight film that excludes Walker, Kelvin Bryant and a few others would be fairly brief and uneventful. Often the play is erratic and sluggish. Most NFL coaches, owners and general managers have either paid the league scant attention or offered criticism far milder than Letterman's satire.

"I haven't watched it much," said Miami Dolphins Coach Don Shula. "I'll tell you what did catch my eye. That was when I saw a guy we drafted, Anthony Carter, return a punt for a touchdown. That caught my attention."

No one, not even Chicago Blitz Coach George Allen in his most zealous and pugnacious mood, is willing to compare the football played in the USFL to that of the 64-year-old NFL.

"By the USFL's own admission the quality isn't near what it is in the NFL," Cleveland Browns owner Art Modell said. "Most of the people they use have been waived by the NFL at one time or another.

"I don't think quality is a real factor in their survival. You see things like 28-yard punts and fumbled snaps repeatedly. It's got a very long way to go. But listen, we have some awful teams in the NFL, too. But as a television product, as long as the outcome is in doubt, and no one team constantly dominates, there's hope for them. It doesn't have to be quality football. Purists won't touch the USFL, but that's only a small number."

Paul Warfield is now Modell's assistant in Cleveland and is best known for his brilliant career as a wide receiver for the Browns, Dolphins and, briefly, for Memphis of the defunct World Football League.

"When I was in the WFL there were only a few guys other than Larry Csonka and Jim Kiick and myself who could play in the NFL," Warfield said. "I'd think the USFL is stronger than that. They (the USFL) have a few No. 1 draft choices that could have played in the NFL and I guess they still could.

"Quality may not be the big question. Take me. I'm a traditionalist. In the spring, with baseball on, and track and field, there's no question what I'm going to watch. The same thing with a lot of people I know who love football. It's a fall sport. The USFL has to do a lot of converting."

Others in the NFL have been even less impressed with the new league. Pittsburgh Steelers Coach Chuck Noll called the USFL the "minor leagues." And New York Giants General Manager George Young said, "I've been to a couple of games and I've watched it on television a number of times. They're doing the best they can. But you have to remember with the old AFL, there were a lot fewer NFL teams around. It may be more difficult for the USFL to get quality players because there are just more teams."

San Diego Chargers owner Gene Klein said, "It took the AFL five or six years to gain parity with the NFL. Because there are so many more teams now, the talent's more divided up. It would take a lot longer for the USFL to catch up."

When the American Football League began in 1960 with eight franchises there were only 13 teams in the NFL. Now the NFL has 28 teams and the USFL has 12, with plans to expand to 16 next year and more in the future.

Before the USFL played its first game in March, owners and coaches proclaimed that fans would enjoy a wide-open style of play. Coaches such as Hugh Campbell and Ray Jauch came to the USFL from the Canadian Football League, where the ball is in the air more often than not. If some fans were tiring of a conservative brand of NFL play--clearly fans who had never seen the San Diego Chargers play--they would love to see a flamboyant alternative.

Or so the advertising went.

"From what I've seen, it's been a very conservative league," said New York Jets Coach Joe Walton. "They don't seem to risk much on offense. It looks like a pretty defensive game to me so far."

"Quarterbacks. The problem has to do with quarterbacks," said Mike Faulkiner, once the Federals' personnel director and now an assistant to Walton. "One of the mistakes I probably made with the Federals is that I never made a big enough case to go for a quality, big-time quarterback. That and an offensive line is what you need more than anything else.

"If I was with a USFL team now, I'd go after a guy like Dan Fouts with everything I had. If it takes $1 million a year, so what? If you don't build your franchise now there may not be any tomorrow. And then you've lost a whole lot more than $1 million a year."

Faulkiner, who once worked as an assistant to Allen when he was coach of the Redskins, tried to estimate the overall quality of the USFL:

"If the Philadelphia Stars or the Chicago Blitz were to play the Colts, they (the USFL teams) would lose six out of 10 times. A team like the Redskins would win every time. The best teams in the USFL would be competitive in the Canadian league but they wouldn't wipe up, not by any means. And I don't think some of the better running college teams like Nebraska would win in the USFL but a team with a varied attack, like Brigham Young or Penn State, would do pretty well."

Asked to make a similar evaluation, the New England Patriots' director of player development, Dick Steinberg, said, "I wouldn't touch that question. I can't say a thing about it. The last time I came out with a critical statement about them, I got in trouble. The whole thing led to (Tampa Bay Bandits owner) John Bassett challenging us to a game. People have told me to stay away from the subject from now on."