The risks of working at cornerback include the possibility you will be undressed, as the coaches say, by a slick receiver who fakes this way to cause your shoes to fall off and then fakes that way, loosening your belt, before flying downfield as you reach with both hands to cover your bare bottom.

The possibility was made into shivering reality for Darrell Green Friday night when the Redskins' rookie cornerback came unbuttoned every time Jimmy Cefalo cruised past him. On one memorable pattern, Cefalo did a stutter step that froze Green; then sped away three strides into a reverse pivot that spun Green like a top before, catching the pass, Cefalo eluded all but Green's groping, lucky hand tackle.

Another time, when it was Green's job to cover behind a blitzing safety, he missed a tackle on Duriel Harris, perhaps touching him with a pinky, that gave the Dolphins a touchdown.

We could go on. Some notebook scribblings: "Cefalo turns Green inside-out but pass OB . . . Green illegal contact on Harris, puts ball at 10 ....Cefalo takes Green to goal line and turns for catch at 2 . . .Green knocks down pass to Cefalo, :44 left in 2nd quarter, first time touched ball . . . .Clayton beats Green on fade in corner of EZ, TD . . . .To find Green, look for open M receiver; he's two steps behind him."

Maybe a No. 1 draft choice can hide in the offensive line, where only his mother and his coach watch him. But if you're Darrell Green, a world-class sprinter and small-college all-America defensive back who is the No. 1 pick of the Super Bowl champions, you can run but you can't hide.

The Redskins' 38-7 loss to Miami was disturbing on several levels to anyone anxious to see the team repeat its success of 1982. Not since the 0-5 start of two seasons ago have the Redskins been so thoroughly beaten. "It's a good time for us to do some thinking," Coach Joe Gibbs said. "It's time to do some real soul-searching."

The defeat is an object lesson in Gibbs' preaching that this Redskins team must play near its full potential to win. Any reduction in efficiency by any unit can upset the balance that enabled a bunch of overachievers to beat more talented teams. Miami's 38-7 victory six months after the 27-17 Super Bowl defeat is a clear signal: the Redskins' precious balance is in danger now.

Without Fred Dean and with Mark May playing hurt, the Hogs have gone back a step. With Art Monk again on crutches, the passing game suffers. Defensively, the Redskins still have no pass rush and, worse, their secondary without veterans Jeris White and Tony Peters can not compensate for the linemen's ineffectiveness.

Green, for instance, should be no more than a reserve cornerback, learning his trade behind the master White. Only 5-feet-8, Green has a physical liability that he will overcome only with anticipation born of experience. But White is holding out, forcing the Redskins to put Green out there where slickers named Collinsworth and Cefalo have left him, to use President Reagan's metaphor, wearing a skin suit.

The depth of the Redskins' secondary problem is measured in two numbers: 12 and six.

In the Super Bowl season, the Redskins gave up only 12 touchdown passes in 13 games.

Beating Cincinnati last week and losing to Miami this, the Redskins gave up six touchdown passes.

Along with Green, the Redskins have another rookie, Ken Coffey, at strong safety. Coffey is off the 1982 injured reserve list and only now is facing game competition. With no pass rush and with unproven people beside him, even free safety Mark Murphy has looked vulnerable, beaten deep twice by Miami when simply outrun. Only Vernon Dean, at one corner, has been solid so far.

And the cursed Cowboys come to town in two weeks and a day. One imagines the silver-hatted air force of Tony Hill, Drew Pearson and Danny White had a real good time watching the Dolphins pick on the Redskins' secondary.

"A long, hard night," safety Curtis Jordan called it. "A transition period for us new people," Coffey said. "It's only a matter of time and Darrell Green will be a great corner," Dean said. "I feel good about our safeties," Gibbs said, adding of the corners, "We'll have to work our way through it."

"Darrell just needs time to grow," said Richie Petitbon, the Redskins' defensive boss. Pettibon meant growth, as in experience, because any kid corner is suspect. The coach also wishes the little guy could grow taller. "He has everything but size." Then, through clenched teeth: "If he keeps missing tackles--that scares me more than anything."

How bad was it?

"Darrell made enough mistakes to last a lifetime," Petitbon said.

"The mistakes I made I know I can correct," Green said at his locker, where he sat laughing and joking with buddies. For a fellow beaten nine ways to Sunday, Green was a chatterbox of joviality and confidence. "I know exactly what I did wrong. I know that I have to play smart as well as use my athletic ability. What I'm thinking about is being aggressive. I have to go up and take the ball. It's my ball. I can do it, I've been there before.

"I'm going to come back strong. I'm going to be a Redskin for a long time. Hey, Darrell Green still believes in Darrell Green."