SEAVER MASTERS MIX OF ART AND SCIENCE
TWO items caught the attention of a visitor at Tom Seaver's locker stall in the White Sox clubhouse. This was on a late afternoon before a recent ball game. One of those items was The New York Times crossword puzzle that the veteran pitcher had begun before being interrupted: He had just completed 4 Down, ''Spud feature,'' three letters (he penned in ''eye'') and 13 Across, ''Bailey, Belli et al.,'' seven letters (he wrote ''lawyers''). The other item was a White Sox cap hanging on a hook. It was a dark blue cap inscribed with dry perspiration stains, perhaps worn in his last outing a few days previously.