Welch was the third starting pitcher in the rotation for the 1989 World Series champion Oakland A's, compiling a regular-season record of 17-8 and recording a win in his only start in the American League Championship Series against the Toronto Blue Jays. In an odd twist of fate, however, Welch did not throw a single pitch against the San Francisco Giants during the World Series itself. Just minutes before Welch was to take the mound in Game 3, Candlestick Park and the Bay Area were struck by the Loma Prieta earthquake, which caused extensive damage in the region and forced the postponement of the game. When the Series was resumed 11 days later, A's manager Tony La Russa opted to re-use his Game 1 starter, Dave Stewart, for Game 3 in place of Welch, and his Game 2 starter, Mike Moore, for Game 4 in place of originally scheduled starter Storm Davis. The strategy worked, as the A's swept the Series in four games giving him his second World Series.