Jockey Jorge Belasquez thought Pleasant Colony was bothered by the presence of a cameraman in the starting gate for the Belmont Stakes.

Owner Thomas Mellon Evans thought his colt may have been upset when somebody set off a firecracker as he was walking to the paddock.

Trainer John Campo said, "The pace beat him. It was a terribly run race."

There is always an outpouring of excuses when a heavy favorite loses a major race. But the explanation for Pleasant Colony's loss to Summing on Saturday was perfectly clear: he was not a good enough horse to win the Triple Crown.

It is no accident of history that the winners of the Triple Crown have been indusputable great thoroughbreds. They must be able to handle different distances and different surfaces, and cope with different types of racing situations. Pleasant Colony doesn't have this type of versatility.

He had scored all three of his victories this spring -- in the Wood Memorial Stakes, the Kentucky Derby and the Preakness -- with virtually identical performances. He had raced in the back of the pack early, then seized the lead a rush on the final turn. But one-dimensional stretch-runners can get themselves into trouble in many ways, by running into traffic or losing or being hurt by a slow pace in front of them.

When the pacesetters in the Belmont had loafed through the first six furlongs in 1:14 1/5, Pleasant Colony should have been vying for the lead. Instead, he was nearly 10 lengths behind, spotting the horses in front of him a virtually insurmountable advantage. Velasquez surely recognized the slow pace, but he also knew that making a move at this point wasn't Pleasant Colony's game. By the time he made his customary move on the final turn, Summing already had taken control of the race.

Everything that could possibly go right for Summing did go right. He saved ground all the way, got through on the rail at the perfect moment and benefited from the slow pace. He is probably the worst horse to win the Belmont in the last decade. Needless to say, this opinion is not shared by trainer Luis Barrera, who was irked by the apologies being made for Pleasant Colony and, in particular, the theory that the CBS cameraman bothered him.

"How come it bothered his horse and not mine?" Barrera asked this morning. "They have to come up with a better excuse. I'll tell you what really happened: the best horse won."

Barrera is wrong. The best horse didn't win the Belmont. The best horse in the race was Highland Blade. Like Pleasant Colony, he had to come from far behind and was hindered by the slow pace. In fact, with half-mile to run, he was 1 1/2 lengths behind the favorite. And Highland Blade lost more ground than Pleasant Colony, rallying wide on the turn. Yet he missed catching Summing by only a neck, and beat Pleasant Colony by 1 1/2 lengths. If these horses raced at the Belmont distance again, and the breaks of the game were evenly distributed, Highland Blade would have annihilated Summing.

There will be plenty of opportunities to verify this thesis, and to judge more accurately the relative ability of this year's 3-year-olds. The top Belmont finishers will probably be pointed for a rematch in the Travers Stakes at Saratoga. They will also get challenges from Lord Avie, last year's 2-year-old champion who has recovered from an injury, and Five Star Flight, a colt who is just about to show how good he is.

It is quite likely, at the end of the season, that Pleasant Colony will have affirmed that he is the best 3-year-old of 1981. He has enough ability to be a champion of his age group. He did not have enough ability to be listed for all time with great horses like Count Fleet, Citation and Secretariat who were superior enough to win the Triple Crown.