PASSAGE of a ROOKIE : Aaron Cox's Saga, From South-Central Los Angeles to the Rams

You're Aaron Dion Cox, NFL rookie and property of the Los Angeles Rams.

Cox had always dreamed of playing for the Rams, and last April they made him a first-round draft pick. He'll be paid about $1.55 million over the next four years to play wide receiver. He's 23 years old and living a dream come true. Aaron Cox, new millionaire, should be very, very happy.

But Cox is nervous. He's just arrived at training camp, the National Football League's brutal rite of passage. He's an untested rookie, a question mark, and he's about to go through eight weeks or so of trauma, self-doubt, embarrassment, pain and frustration, broken by rare moments of exhilaration. Quite simply, Cox is going to find out whether he's good enough to play with the big boys. He knows that if you don't cut it, you're just another ex-college jock on the job market.

Cox begins with a distinct advantage: He's rookie royalty. In this year's NFL draft, he was the 20th of 333 players chosen. That explains the big-time contract, the news conferences, the hoopla--and it also explains Cox's apprehension.

Even as the April 23 draft approached, as scouts and coaches predicted his first-round selection, Cox remained cautious. He told friends that there would be no party at his Tempe apartment on draft day, that it would be just him and the ESPN sports channel.

"That's the way I wanted it," he says. "It's just the way I am. I'm pretty much a loner anyway. I like to be by myself--a lot. And this was a big part of my life."

The truth is, Cox was scared that he might be chosen in a later round.

At the last moment, he let former Arizona State teammate Skip McClendon and McClendon's father watch the telecast with him. A year earlier, McClendon had been selected by the Cincinnati Bengals. "Now (Skip) wanted to see somebody else's reaction," Cox says.

The Rams, who had two picks in the first round, took UCLA running back Gaston Green first. After that, Cox's phone rang. The Rams were asking for the phone number of Cox's agent. Five minutes later the phone rang again. It was his agent, Ernie Wright.

"The Rams are going to take you," said the no-nonsense Wright, who played tackle for the Chargers in Los Angeles and San Diego and the Cincinnati Bengals in the '60s and early '70s. He now manages about 15 NFL players.

"That's fine, but I still want to hear them say that," Cox said.

Minutes before the Rams' turn, the phone rang once more. This time it was Coach John Robinson welcoming him to the team.

Two hours later, Cox was on a plane to Orange County's John Wayne Airport. At an afternoon news conference, he held up his Ram jersey for photographers. The next day he flew back to Tempe. Things were happening fast, yet Cox remained surprisingly calm.

"I didn't feel at all different," he says. "I thought I might have. All I said was: 'They drafted me--now I have to perform.' I guess that added a lot of pressure."

It's a strange, tough business. In April, Cox is a hotshot NFL draft pick with all that hometown publicity. By July, linebackers are trying to punch holes through his sternum. There is no grace period, no leisurely period of adjustment. Professional football is a big business in which Darwin's theory is at work every day. You block. You run. You catch. You kick. You tackle. If you don't, you're just another name on the list in tomorrow's sports section under "Cuts."

Unlike the veteran players who falter, rookies rarely receive second chances. They only have those eight weeks--the length of training camp and the exhibition season--to make an impression. But odds and audition times vary. Rookie free agents are the long shots of the game. Late-round draft picks maybe get a moment or two of attention. Middle-round selections earn consideration. Early round choices, such as Cox, are near-locks. They have to be; they cost more.

But Cox takes nothing for granted. "I'm thinking that if I go in there and just be average and there's somebody better than me, there's a chance I might not be around," he says. "Then I heard that I would have to be pretty much a flop to get cut, and even then they might keep me around because of the signing bonus, tell me to try it again next year.