In the history of the Metropolitan franchise only one player has suited up for the team who was born in Milwaukee. That would be sprite-sized (as described by the New York Times) second baseman Jason Hardtke. The name was pronounced "Hard-Key" and that was the key to his game, playing hard, because otherwise, he wasn't going to play much at all. He's listed at 5-10, 175, but my guess is that sprite-sized players aren't quite that big, so that may be an exaggeration. By my recollection, Hardtke was a middle-class man's Kelvin Chapman, though Chapman's 172 games with the Amazins' dwarf Hardtke's 49. He was a decent player, who tried hard and deserved to be on the team, but since he wasn't flashy and didn't excel at any particular trait, the team decided he wasn't worth as much of a shot as someone else. I found a Virginian Pilot story from 1996 referencing how Hardtke grew up in San Jose (he moved from Wisconsin at a young age). He
A blog devoted to cataloguing New York Mets walk-offs and other trivia. For those unaware of the definition of walk-off just replace the term with the words "game-ending" and you should have a much better understanding of the phrase.