This may have been Joe Greene's meanest preseason yet.

"This is the toughest thing I have ever tried to do," he said, referring to his efforts this year, at age 35, to learn a whole new sport called broadcasting. "After that first game, I was really drained. I felt as though I had played a football game."

Greene retired last year after 13 seasons as a star with the Pittsburgh Steelers. He did a commercial for Coca-Cola in 1980 that made him famous off the field, and in nine days last summer he made an NBC movie (based on the commercial), which, if it didn't help make him more famous, at least guaranteed his kids' college education.

This season he becomes one of the newest players on television's annual celebrity color commentator circuit. It's a new life; and not so easy, either. The only people intimidated by Greene's 6-foot-4, 260-pound frame are the guys who make the blazers for CBS Sports. Everybody else keeps poking and buzzing urgently in his ear for him to speed it up, project yourself, be natural, louder, say this, describe that, hurry up, relax.

"These guys have been very patient and they've been helpful," said Greene of Terry O'Neil, CBS' NFL executive producer, and O'Neil's colleagues.

For the past month, Greene has shared a microphone with CBS play-by-play veterans Frank Gleiber and Dick Stockton for all three of the network's preseason games. But in a unique training arrangement for CBS, everything done and said by Greene and his partner has gone into a tape machine instead of on the air. The Greene team sat in a booth, just like A-team announcers Pat Summerall and John Madden. These were dress rehearsals, in effect, for the soft-spoken Greene's world premiere as a color analyst--the Redskins at Tampa Bay on Sept. 19.

"From the little I know about what goes on in the truck," Greene said, "it takes some time and it takes concentration for these guys to get up and to do this with me and not to be on the air . . . it can be trying."

"It's all new," said Greene, who originally tried out for NBC (which covers the American Football Conference and which would have been naturally easier for a former Steeler). Greene was lured to CBS and the NFC, he said, by O'Neil's promise of this training time.

"We might've hired him if we could've come to terms with him or if we had decided to have two (color) people in the booth," said NBC's NFL executive producer, Ted Nathanson. "Joe Greene is a very, very nice guy to work with. I think he's got to work like crazy at it."

Nathanson auditioned his NFL experts for the first time this year--Greene, Bob Griese and Dan Pastorini--and decided on Griese. Nathanson has put Griese in a booth with Charlie Jones during the preseason for the same kind of off-the-air dress rehearsals.

"Basically, you're looking for some articulate, bright personality that comes across on television," said Nathanson, "someone who can describe why things are happening, give an overview, explain strategy. If they have a sense of humor, that's all the better."

Greene said the most difficult aspects of color commentating are the reporting--which O'Neil this year is insisting his analysts do, arriving early, asking questions, watching film--and the "technical aspects." These include, he said, "being able to talk, without pausing to listen, when someone else is talking in your ear," and "fitting the information I have about a ball game into prescribed slots, 15- to 20-second slots." Finally, Greene said, he has been grappling with every producer's ultimate wish: being intense while sounding relaxed.

"It (broadcasting) wasn't something I thought I would do (when he retired)," Greene said. "I didn't even have it in my mind. The opportunity presented itself, first in the form of NBC. I auditioned. I was terrible. Then CBS became interested, and . . . I did an audition for them. I was terrible.

"I didn't want to go out and make a fool of myself. Who wants that? But I did want to try it. I know when I do go, I'll go with some measure of confidence. I won't be where I want to be, but at least it won't be all new to me."

CBS' other NFL pairing this year, besides Summerall-Madden and Gleiber-Greene, includes No. 2 team Jack Buck and Hank Stram, who've been teamed for years on the Monday night radio broadcasts. Buck replaces Vin Scully, who told CBS earlier this summer he didn't want to do football for the network. Scully has not yet signed with NBC, as rumored, and will continue doing the Dodgers in Los Angeles and will call the World Series for CBS Radio.

CBS will hook up Tom Brookshier with newcomer Wayne Walker, a former Detroit Lions linebacker who spent three years with CBS in the mid-'70s and since then has been doing the 49ers on radio in San Francisco. Dick Stockton will team with Roger Staubach, Tim Ryan with Johnny Morris, and Jim Kelly and John Dockery will return. Charlie Waters and Calvin Hill, CBS says, will do a handful of games.

Phyllis George will rejoin Brent Musburger, Irv Cross and Jimmy the Greek for the in-studio "NFL Today" inserts this year. The powers-that-be at CBS hope to get her "into the field" more often than in recent seasons because they think she's a good reporter/interviewer.

The No. 1 team at NBC remains Dick Enberg and Merlin Olsen, with a fight for the No. 2 spot between the teams of Bob Costas/Bob Trumpy, Don Criqui/John Brodie and Jones/Len Dawson. Other pairings are Marv Albert and Jim Turner, Phil Stone and Gene Washington and Jay Randolph with Griese.

NBC's "NFL '82" -- the pregame, halftime and postgame conglomeration, new this year since the departure of host Bryant Gumbel -- will be coanchored by Len Berman and Mike Adamle, with reporters Byron Day and Bill Macatee and commentator/oddsmaker Pete Axthelm.

ABC hadn't decided yet whether Frank Gifford and Howard Cosell would be joined in the booth by Fran Tarkenton or Don Meredith -- or, as last year, by both on a rotating basis. Meredith is recovering from surgery he underwent earlier this summer, an ABC spokesman said. Graphic: Photo by Harry Naltchayan; Greene: Broadcasting is "the toughest thing I have ever tried to do"