That is just plain astonishing.
"The first Major League game ever played, a National Association contest between the Cleveland Forest Cities and Ft. Wayne Kekiongas on May 4, 1871."
Probably 16,000 guys have played ML baseball in the intervening 140 years. Moyer pitched in the AL for a good long time and didn't "face" pitchers during that span. But that would mean that he's pitched to well over 1,300 different batters. Crazy.
The first ML batter Moyer faced, in his debut for the Cubs in 1986 was Ron Roenicke (Gary's brother) who is currently managing the Brewers.
That the first hitter he faced is a ML Manager beats saying that the first batter you faced died of natural causes, I guess. lol