Every time he walked into the Belmont Park paddock last month, boos and taunts rained on jockey Angel Cordero Jr.

"Hey, ya gonna stiff another favorite?"

"Angel! Angel! I hear they're getting your jail cell ready, Angel!"

They cursed him in the paddock. They booed him in the post parade. They booed him when he lost. They booed him when he won.The abuse was so severe that at least one owner stopped using his services because he was too embarrassed to stand near Cordero within earshot of New York's racing fans.

The derision was the culmination of months of controversy and scandal that have enveloped Cordero. The pressure on him was so crushing that it could have destroyed almost any athlete's self-confidence and wrecked his performance. Cordero responded differently.

"When it's a beautiful day, when everything is going right, anybody can perform good," the jockey said, "but when everybody's down on you, that's when you can show how good you are. Whenever I'm under pressure, I ride a little bit better."

At the Saratoga meeting that ended Monday, Cordero did more than ride a little bit better. He did more than win the riding title for the fourth straight year, despite a suspension that kept him out of action for a week. He rode with consistent dazzling brilliance. To an observer who didn't get to watch the giants of the last generation, Eddie Arcaro and Bobby Ussery, in their prime, it seems inconceivable that any man could ever have ridden horses better.

Cordero not only has the requisite physical endowments for a jockey -- the strength, the reflexes. He has the intelligence to perceive the idiosyncracies of a race track and the ability to adjust himself to them.

In the ninth race here one day, he was riding a sore-legged plodder named Billy Caesar, whom almost any knowledgeable handicapper would have dismissed at a glance. Speed horses had won seven of the first eight races, and Billy Caesar's record did not indicate that he possessed an iota of early speed.

Cordero knew all this, too. "That day," he said, "they had scraped the track and all the winners went to the lead and got on the rail. In the post parade, too, 'I could tell that the rail was the best part of the track.

"In the parade I told the pony boy, 'Turn me loose.' That horse is a lazy SOB but I really warmed him up: jogged and galloped, jogged and galloped." Then when the gate opened, Cordero started whipping Bill Caesar repeatedly -- not a common procedure at the start of a long race. But the confirmed plodder battled head and head for the lead, got to the rail and ran away with the race. He had done for Cordero what he had never done for another jockey.

Cordero is a natural, a born horseman. He grew up in Puerto Rico, where his father and numerous other relatives also were jockeys, started his riding career there and came to the U.S. in 1962. He fared so badly at first that he almost gave up in despair and went back home. But he persevered. He won his first national riding championship in 1968. He captured the Kentucky Derby with Cannonade and Bold Forbes. His mounts earned more than $5 million in both 1977 and 1978. At the start of 1979, he might well have thought that all the rough times were behind him. They were not.

After the Florida Derby at Gulfstream Park this winter, trainer Bud Delp and jockey Ron Franklin accused Cordero of conspiring to hurt Spectacular Bid. That triggered a feud that simmered for months and finally erupted with a fight between the two riders in the Belmont jockey room.

The accusations against him had been wrong, and a more statesmanlike rider might have ignored Franklin. But Cordero is a proud man, and when his pride is wounded, he can respond with vindictiveness. He rode in the Preakness, and then again in a race before the Belmont, as if he were out to "get" Franklin. In the public's eye, he became the villain, the established veteran waging a vendetta against the groping apprentice.

That image contributed to his impopularity this summer, but the Spectacular Bid controversy already has passed and soon will be forgotten. Corder's other problems will not vanish so easily.

In a Sports Illustrated article this past winter, confessed racefixer Tony Ciulla named Cordero as one of the riders who had been involved in larcenous races during the early 1970s. Ciulla has testified at race-fixing trials in other states, and juries have been up-holding his version of events. For months now, reports have been circulating in New York that a grand jury will hand down indictments against Cordero and several other prominent riders.

With a sword hanging over him, Cordero might have been so distracted that he couldn't concentrate or function properly. "It might have happened that way," he said, "if the accusations were true. But I'm innocent, and the day will come when I'm going to prove it."

"Still," Cordero said, "all this has hurt my reputation. A lot of the newspapers have been knocking me, and the public picked up on it." The combination of the race-fixing charges, the feud with Franklin and a mild slump at Belmont had triggered the boos and the catcalls. His riding performance has silenced them all now.