How many times must a man be hit over the head to realize that's dangerous? Which concussion is one too many? Why in the name of sound wisdom are you playing tonight against the Bengals, Terry Metcalf? We pretty much understand the answer you'll be giving very shortly here. But dammit, we'd like to look at you and see Roger Staubach instead of, say, Doug Kotar.

Metcalf lately has been poked and probed, scanned about the mind and nearly every other part of a relatively tiny body that has lasted about six years longer than lots of larger ones in pro football. Cautiously, competent and compassionate men have told the Redskins' special special-teamer that if he wants to stick a head that's been hurt more often more seriously than most back into National Football League combat to go ahead.

Metcalf wants it.

Now.

Two months ago, two weeks ago even, Metcalf very likely would have walked away without a whimper, as the concussion-prone Staubach had. Now he must be convinced he no longer belongs in the NFL. Talk won't do it. Not even from his dear friend, Redskins Coach Joe Gibbs. Metcalf must be shown, by his peers, on the field, and that means charging toward a bunch of Bengal crazies in Riverfront Stadium.

Whether consciously or not, Gibbs often talks about Metcalf in the past tense. He probably is torn in two directions, not wanting Metcalf to risk permanent injury but also not daring to deny a dream to a player who has meant so much to him.

"I'm doing it 'cause I want to," Metcalf said after practice the other day, a familiar routine in which he gave himself more work than the coaches did. "And I think I still can. Financially, that's not the problem. I can be okay without the game. But I think I have one, maybe even two, years in me.

"This'll be one way to find out.

"If I don't (play well), I won't (play again). If I can't cut it, I'll know for sure myself. Because all during camp I haven't had that chance to find out: whether I can or cannot. I personally think I can."

How can he tell?

"I think I'll be in some third-down situations," he said, "and I can tell by whether I can move, get away from a guy. On special teams, I can tell because the positions I'm in I've got to be hitting people. I did some of that last year, for the first time, and I enjoyed it, enjoyed being the hitter instead of the hittee."

Once he took two Patriots out with one block, and Mike Nelms scored on a 75-yard punt return.

"To me, that was as good as scoring myself," Metcalf said. "That's the kind of charge I got (from the block). If I go out there (tonight) and go through it kinda half-steppin' or not wanting to do it, I'll sense it. But right now I feel that I want to do it. And I'm gonna go out and give it the best I've got."

Gibbs has yet to see anyone go harder longer. The player and coach became close when Metcalf was a third-round, although not obscure, draft choice for the Cardinals in '73 and Gibbs was an offensive aide.

"He's the only guy I know," Gibbs said, "who thought he ought to score on every play."

There was even more motivation for that when Metcalf failed by a yard or so of scoring sometimes as a rookie. He would take the ball most of the way to the goal line, and the Cardinals would bring in some Jim Otis-like tank to make sure it got all the way safely. Metcalf has fumbled frequently.

"Next season, I told myself: 'They can have the one-yarders. I want the 60s and 70s,' " he said.

Three times a Pro Bowler, Metcalf has run at least 75 yards for a touchdown, turned a pass into at least a 68-yard touchdown, returned a punt at least 69 yards for a touchdown and taken kickoffs 94 and 93 yards for touchdowns. When the ball simply had to be delivered quickly long distance, Metcalf was better than Federal Express.

But not as durable.

That 5-foot-10, 185-pound frame has produced more than 10,000 combined yards in the NFL and more than 4,100 when Metcalf was forced to the CFL by Cardinal cheapskates. It also has taken more than its share of what are known in the business as "heavy taps."

The most severe, however, came during an April basketball game, a concussion so severe and lasting that nearly a month later his normally fine writing style became spastic scribbles. That problem righted itself. But he still was scared by lack of coordination sometimes in his right side. He had trouble dribbling a basketball.

The '81 Metcalf would have been among the top finishers in the Redskins' 12-minute run in training camp; the '82 Metcalf barely finished the required six laps. Also, he would scamper beautifully one play and horribly the next. For no apparent reason.

Metcalf seemed as uneasy as Gibbs about testing himself in games, until he was examined by a chiropractor friend of Jeris White's in Tampa Bay after the Redskins' exhibition with the Bucs less than two weeks ago.

"He took X-rays of my head, my neck and my spine," Metcalf said, "and showed me what the problem was. My spine was" -- he paused, his tone becoming part wonder and part fright -- "crooked."

That'll happen if you collide with too many Bill Bergeys.

"It was pinching off nerves leading to my arm and leg," he added.

So the man "adjusted it."

"I got instant relief," Metcalf said. "Instant strength. I had high blood pressure before; after, it went down. That's why I'm confident I'll be okay. He showed me what the problem was. It's possible that could happen again, with the right shot and all. But he said my chances of getting hurt are no worse than the next player."