How did long shot Temperance Hill win the Belmont Stakes? Why did Codex, the seemingly superior horse in the field, run so dismally?

Answering such questions is never easy, because so many different factor influence outcome of races.When a Monday morning handicapper offers a pat explanation -- such as the ever-popular, "He couldn't get hold of the track" -- he is usually guilty of a gross oversimplification.

To comprehend what happened in a race, a handicapper should first look at the final time and decide whether the horses ran well or ran badly. On Saturday at Belmont Park, they ran badly. Temperance Hill's winning time of 2:29 4/5 was the worst since 1971, and even though the track was sloppy it was not extraordinarily slow.

Three weeks earlier, Codex had beaten Genuine Risk in the third-fastest Preakness in history. Two weeks before that, Genuine Risk defeated Rumbo in a respectably fast Kentucky Derby. If any of these horses had run his normal race on Saturday, he would have won the Belmont. Because they didn't, Temperance Hill could win virtually by default.

The colt had never run so well as he did on Saturday, and there were a number of reasons for his improvement. A plodding stretch-runner, he surely liked the 1 1/2-mile distance. He was the only horse in the field equipped with mud caulks, which give horses better traction on a sloppy track. His previous start had been on the turf, and jockey Eddie Maple observed, "For some reason horses just seem to run back dynamite off that."

And Temperance Hill may simply have been feeling very good on Saturday. Before the race, I was standing next to two astute judges of horseflesh, my colleague Clem Florio and Newsweek's Pete Axthelm, and both pronounced him the best-looking horse on the track. Neither bothered to bet him at 53 to 1.

Such a confluence of positive factors will probably never happen to Temperance Hill again. Trainer Joe Cantey was ambitiously outlining plans this morning to run in Belmont's Dwyer Stakes and Saratoga's Travers, but I suspect his colt's career is going to be all downhill from here.

Codex's future, and his performance in the Belmont, are somewhat harder to assess. Trainer Wayne Lukas explained his seventh-place finish by saying, "He just couldn't handle the track." Jockey Angel Cordero Jr. had said the same thing after the race. They may be right. But the key to Codex's performance was more likely the fact that he was racing without Butazolidin for the first time in his career.

The drug is legal in Codex's home state of California, and it was legal in Maryland at the time of the Preakness. But it is forbidden in New York. When Codex was training at Belmont in the mornings, backstretch observers thought he looked stiff and choppy. When he came onto the track Saturday, Florio -- whose word I take as gospel in such matters -- said he was moving much less fluidly than he had before the Preakness.

Lukas had always denied that Codex needed bute for some particular physical problem, but trainers' statements about medication and soundness must always be viewed with some skepticism. Since a colt's future worth as a stallion will be partly determined by his physical soundness, no trainer is going to say, "My horse is a basket case and he can barely pick up his feet if we don't juice him up."

The trouble with this on-and-off use of Butazolidin is that there is no way to assess the impact of this factor. No handicapper could begin to guess how the lack of bute would affect Codex in the Belmont; probably Lukas couldn't either.

That is as good an argument as any for the nationwide prohibition of bute and other medications. It is complex enough to judge the basic handicapping factors of speed, class and condition without adding a new one that distorts the very nature of the game.