to find in baseball encyclopedias. Adalberto Mondesí briefly held this distinction in 2015, but later made his regular season debut on July 26, 2016. John Paciorek. Paciorek played one game with the 1963 Houston Colt .45s on the last day of the season. He came to the plate five times, and did the following: two walks, three singles, three RBI, four runs scored, career batting average and on-base-percentage of 1.000. Of the 27 players in MLB history with batting averages of 1.000, Paciorek is the only one with three at-bats. St. Paul Saints. In 1884, the Union Association began operation, and is listed in many sources as a third major league. However, the league faced multiple problems, including an uneven distribution of talent (the league champion St. Louis Maroons went 94–19) and poor attendance in a country that suddenly was oversaturated with baseball teams. As the season wore on, teams began to fold, and the league scrounged around for replacements. The last of these replacements were the minor-league Saints (Apostles), an entire team that got a cup of coffee when they were invited into the Union Association. They played exactly nine games, all on the road, at the end of the season. The Saints went 2–6–1. Three other UA teams played 25 games or less, with the Saints playing the fewest. The Union Association folded in January 1885. (Although the league is conventionally listed as a major league, this status has been questioned by a number of modern baseball historians, most notably Bill James in The Bill James Historical Baseball Abstract. James and other baseball historians have noted the league's extreme instability and lack of major-league talent; James has also found that the contemporary Baseball Guides didn't consider the Union Association to be a major league.) Moses Fleetwood Walker and Welday Walker. Moses Walker played 42 games for the 1884 Toledo Blue Stockings. His brother Welday also played for Toledo that year, debuting after Moses and playing for six games. The Walker brothers are the first known black major league baseball players, predating Jackie Robinson by 63 years. The Toledo franchise folded after 1884 and player boycotts (Cap Anson being a ringleader) upheld baseball's color barrier. (Recent research indicates that William Edward White, who played one game in 1879, preceded the Walkers, although White's ethnicity can't be definitely determined and likely was not known to baseball authorities.) Larry Yount. Yount,