n the tombstones of professional pitchers, the most frequent cause of baseball death is: Tried to come back too soon and blew out his arm.

Jeff Ballard, the best left-hander in the American League last season at 18-8, looks like a 26-year-old who, for the good of everybody except himself, is trying hard to hurt his arm and perhaps damage a fairly promising career.

And the Orioles look like a team that may, while meaning no harm, let him do it.

Last year, healthy, Ballard began the season 9-1. This year, hurt, he's 1-9.

Nobody wants to face the obvious. After two offseason elbow surgeries, and a hurry-up return to the rotation, Ballard's season looks like a washout. He needs rest. Lots of it. Not to salvage this season, but to salvage the next 10.

The Orioles, 11 games out of first place, have little chance in the American League East race. But, until this week, when they finally sent him to the bullpen to miss a turn, they took few ameliorative measures with Ballard except to send him to the mound every fifth day to be shellacked again.

Two weeks of long relief isn't going to do it for this guy. In fact, get up, get down, come back on two days rest, could be a cure worse than the disease.

The Orioles' answer, one that should delight fans everywhere, is to put 6-foot-7, 22-year-old Ben McDonald -- the No. 1 overall draft pick of '89 who was called up from AAA yesterday -- in the rotation immediately after the all-star break and leave him there until he pitches himself out of it.

Probably around 2010.

When Ballard is truly rehabilitated and has slowly regained his arm strength -- and that might be this September or next April -- then give him his former spot as top lefty and don't touch him.

The Orioles need their old Ballard badly -- a soft-tossing southpaw to complement their rising battalion of right-handed smoke dispensers. What they don't need is a Ballard whose ERA is 5.28. Considering his 105 hits and 27 walks in 87 innings, it could be higher. Ballard says his record could be better because the O's have scored only 24 runs in his losses. He's dreaming. He could also be 1-12. He's already given up as many home runs (16) as he did in all of 1989.

To many, Ballard '90 looks similar to Ballard '89. The thought that he's one start from "turning it around" has tempted the Orioles and Ballard all season. "He's always put a lot of men on base," one Orioles official said recently. "He's not as bad as he looks right now. He's been unlucky too." Left unsaid is the Orioles' assumption that Ballard also wasn't as good as that 18-8 mark when he got 5.7 Baltimore runs a start. In baseball, such subtle distinctions can even mystify the pros. And short-circuit careers.

Ballard still has his fine change-up and a passable rainbow curve. That's why he sometimes gets somebody out. But his nice little slider of yore is too hard on his elbow. And his "fastball" arrives six inches too high, a few miles an hour slower than last year and without its characteristic screwball tail.

Take away a man's second- and third-best pitches, then give him an elbow so sore that he can seldom throw between starts (to build up arm strength and sharpen control) and you have a mishap waiting to occur. Ballard's always lived on guts, trickery and control.

Baseball reality changes devilishly. Form seldom holds, especially for pitchers, from one season to another. Yet nobody wants to accept this fact of life. It's unpleasant and inconvenient; so pretend it isn't true. That's how poor seasons become bad ones and sore arms become defunct.

How far do you push a young pitcher who's hurting? Nobody knows. Every case is different. Every fan knows about the Mark Fidrych types who flamed out early. But Warren Spahn probably started a hundred times with discomfort and he still won 23 games at age 42. Everybody's guessing.

The Orioles' latest guess is to use the all-star break to get a slumping pitcher a two-week rest. Skip his turn once, then back him up to the end of the rotation next time around.

If the Orioles are lucky, this vacation will be enough for Ballard to fake his way through the rest of the year, heal over the winter, then come back at his 1989 level in 1991.

"Jeff tells us he's 100 percent now," farm director Doug Melvin said yesterday. "We have to believe him. This is all a mystery to him too."

Why risk a 26-year-old 18-game winner in a lost season? Isn't that foolish?

Especially when the rebuilding Orioles are glutted with pitchers who need the starts Ballard is wasting. Give the ball to McDonald, Curt Schilling and John Mitchell. Before the Orioles know it, they'll want to know what Arthur Lee Rhodes, Chris Myers, Mike Linskey and Mike Mussina are made of.

Stop clogging the pipeline, guys.

"We've been concerned about Ballard's arm all year," Melvin said yesterday. "Before the season, we were saying, 'Why not let him take the first two weeks off. Or even more than that.' Now, we're in another situation. Maybe McDonald and some others will be so impressive that Jeff can get his rest, work out of the bullpen and it'll all be for the best."

The Orioles seem more worried about bringing up McDonald a tad too early than leaving Ballard in far too long. You don't ruin future Hall-of-Famers by bringing them up four months shy of their 23rd birthday. Not when they throw 95 mph and have had four years of top college competition. McDonald should be ready. Not to win. But to start learning in 1990 how to win in 1991. The danger with pitchers past voting age isn't bringing them up too soon but letting them pitch too many innings. Or, as their careers progress, like Ballard, letting them come back too quickly.

Of course, the arrival of McDonald (and Schilling with his Billy Idol ponytail) is Ballard's worst nightmare. He doesn't want anybody usurping his hard-won spot on the staff. This guy took a line drive in the chest last month. Take himself out? He never even rubbed.

Because Ballard has a degree in geophysics from Stanford, he's always had to overcome a rich-college-boy tag. He's just the opposite. He won 18 with slop because he's got moxie. He's more Mike Flanagan than Jim Palmer.

Unfortunately, the Orioles may discover this in September when Ballard comes up with a torn rotator cuff or terminal elbow chips. Oh well, only the 5,000th time it's happened since 1869. No reason to learn a lesson.

It's a pro's job to have the pride to perform and earn his money. Even when it hurts. Sometimes when it's risky.

It's a pro team's responsibility to put its long-term interests, and the welfare of its athletes, ahead of its short-term impatience with losing.

Despite his record, Jeff Ballard has done his job like a pro this season.

Now the Orioles have started to do theirs. They may need to do more.