In a perfect world, the four umpires should be the most anonymous people among the tens of thousands in a major-league baseball stadium.

As long as they carry out their essential but often thankless job with understated professionalism, the "men in blue" theoretically should blend into the ballpark background almost as completely as the groundskeepers.

That ideal is seldom achieved, however, because of the variables of fan biases, inevitable human errors and individual tendencies toward showmanship.

The late John McSherry never was able to vanish into the baseball woodwork, no matter how competently he performed his trade. Weighing in at nearly 400 pounds for most of his 21 years in the National League, McSherry was readily identifiable even to casual fans. Whether perspiring profusely behind the plate or lumbering into position on the bases, McSherry stood out among his peers.

Last Monday, his long-lost battle with obesity cost him his life when he collapsed behind home plate and died of sudden cardiac failure in the first inning on opening day at Cincinnati's Riverfront Stadium. The tragedy was recorded by television cameras and rebroadcast countless times.

McSherry was only 51. The autopsy revealed an enlarged heart and blocked coronary artery.

McSherry's sudden death has turned a spotlight on the serious occupational hazards that come with the territory of umpiring in the major leagues. Umpires travel constantly from April to October, crisscrossing time zones, keeping late hours, eating unhealthy meals at odd times of day, drinking too much, sleeping irregularly and performing under the glare of often-abusive managers, players and fans in all kinds of extreme weather. Many become lonely nomads with no time or desire for family life.

Any cardiologist would label the umpires' regimen a recipe for cardiovascular disaster. It should come as no surprise that many umps are dangerously overweight, with most topping 220 pounds and one, the NL's Eric Gregg, listed at 325.

McSherry's death held a special poignancy for me because I first encountered him back when he was auditioning for a major-league assignment in the Florida Winter Instructional League in the late 1960s. He was among a handful of other promising minor-league umps who worked the St. Petersburg games that featured the top young prospects of several big-league clubs.

Every afternoon during the off-season, future Reds, Astros, Cardinals and Mets would play under actual game conditions with team officials and scouts the only spectators. As a young sportswriter for the St. Petersburg Times, I moonlighted as official scorer.

McSherry stood out even then, more for his skill and commanding presence than his bulk. Only in his mid-20s, he was imposing and savvy enough to handle the insults of both cocky young players and crusty old managers.

Two other young Instructional League umpires also attracted my attention. One was the flamboyant showman Ron Luciano. The other was the intense and humorless Nick Bremigan.

All three made it to the majors, none ever married and each died prematurely. Bremigan, who was called up to the American League in 1974, had a fatal heart attack just before opening day in 1989, one week shy of his 46th birthday.

Nicholas Bremigan