Ordinarily, the Preakness is a variation on the theme of the Kentucky Derby. Five times in the last 10 years the Derby winner has triumphed at Pimlico; twice the one-two-three order of finish has been identical.

But this year is going to be different. Any resemblance between the first two legs of the Triple Crown will be purely coincidental. Pleasant Colony, the Derby winner, is no standout in the Preakness. Woodchopper, the horse who faded to finish 10th at Churchill Downs can win at Pimlico. My money will be on that horse, Bold Ego, Saturday.

The outcome of the Kentucky Derby was not determined strictly by the ability of the horses; mediocre animals beat superior ones by margins of 10 to 20 lengths in several cases. This happened because the early pace of the Derby was the fastest in the history of the race. Every horse who contended for the lead, or even ran near the lead, collapsed. Those who plodded in the back of the pack for the first half mile rallied past the tiring leaders and finished well. The Derby rewarded slowness.

The Preakness won't. It is a 16th of a mile shorter than the Derby, and the Pimlico track is traditionally speed-favoring; horses don't often come from 20 lengths behind to win here. And after the Derby, all the jockeys will be extremely conscious of the early fractions. The Preakness figures to be an honestly run race. The best horse ought to win.

A handicapper trying to pick the winner Saturday must look back at the Derby and decide who ran well, not merely who finished well. And Bold Ego ran about as well as any 10th-place finisher ever has.

The colt came to Churchill Downs after winning the Arkansas Derby with a tough, gritty performance. (He beat Woodchopper by nearly four lengths in that race). In the Derby he contended for the lead with Top Avenger and Proud Appeal, running them both into the ground. Proud Appeal, who was unbeaten this year and valued at $10 million, fell apart and finished 18th afer this exertion.

On the turn, Partez launched a powerful move, passing 10 horses in a flash, looking as if he were going to surge to a big lead. But when he drew abreast of Bold Ego, the leader wouldn't let him by. He kept trying and stayed in contention until there was an eighth of a mile to run. He ran an outstanding race, even though he finished 11 lengths behind Pleasant Colony.

Can he turn the tables on the horses who beat him by so much? I think so, because while Bold Ego was encountering insuperable adversity, everything that could go right for Pleasant Colony did go right. All the speed horses ran each other into defeat. Most of the other stretch-runners encountered heavy traffic or lost much ground on the turns. Pleasant Colony scarcely had a straw in his path for a mile and one quarter. He is a good, honest, racehorse, but I couldn't take 8 to 5 on the proposition that God is going to keep smiling on him so benevolently.

If Pleasant Colony's victory was abetted by optimal conditions in the Derby, Woodchopper's second-place finish was entirely the result of the fast pace. Woodchopper is the worst kind of plodder, but he looked like a whirlwind finisher in the Derby because he made his move when everybody else was exhausted. On the Pimlico track, he will be the victim rather than the beneficiary of his one-dimensional running style.

Bold Ego's principal challenge may come not from the one-two Derby finishers, but from the colt who finished third, Partez. The California invader made a move on the turn at Churchill Downs that was electrifying, and he did it while losing a great deal of ground in the middle of the track. He lost another length or two when jockey Sandy Hawley stood and misjudged the finish line. He has the quickness and versatility that Pleasant Colony and Woodchopper lack.

This Preakness is very competitive and, for a handicapper, very complex. But unlike the years when superior horses like Spectacular Bid and Seattle Slew were dominating their opponents, this race offers bettors the chance to make a decent profit. And if the 10th-place finisher in the Kentucky Derby does win it, the profits could be substantial.