Part one: The American Association Browns, 1882-1891.
By 1891 the American Association is about to topple over—the wealthier owners, like the Browns' Chris Von der Ahe, are no longer willing to float weaker teams to remain independent, and the National League agrees to accept four clubs (but not the 1891 pennant-winning Boston Reds) into the senior circuit. And that, for a decade, is the end of two-league baseball.
The National League hasn't had a St. Louis representative since 1886, and that team was itself a shaky transplant. It was the St. Louis Maroons, who had begun life as the big fish in millionaire Henry Lucas's toy baseball league, the Union Association. Without question the weakest league to be considered "major" by baseball's encyclopedias, the Union Association was Lucas's invention, and operated a lot like a rigged game of Baseball Mogul; he grabbed the best of the players willing to jump from the two established leagues and proceeded to go 94-19 (135-27 in MLB parlance) against a bunch of minor leaguers and has-beens on franchises that were at risk of folding from the moment they began play.
(Posterisk: the end result of this is that, if you're ever wondering who had the best season in St. Louis history, and you're not at all interested in adjusting for context, your answer is almost certainly Fred "Sure Shot" Dunlap, who had the kind of season Chase Utley might put together in the Texas League as the star of the Maroons in 1884. In a league that hit .247/.274/.320 [I'm not going to beat red baron's inspired "Bat Gagnozzi", but if you're looking for a stealthy Matt Pagnozzi nickname "The Union Association" isn't bad], Dunlap hit .412/.448/.621, for an OPS+ of 258.)
After his league collapsed, Lucas went once more to the ATM and came back with the Maroons' entry fee to join the National League, whose St. Louis Original Brown Stockings had folded in 1877. Unable to compete against the Browns, who outdrew everyone else in the American Association, or the National League, the Maroons folded in 1886 and Lucas, having squandered his seven-figure inheritance, became a railroad clerk. (Dunlap, who was probably very disappointed after the UA folded, hit .270/.334/.333 [OPS+ 119] to pace the Maroons in 1885.)
The Maroons were ill-equipped to compete with anybody, save for their hand-picked Washington Generals in the UA, but being in St. Louis didn't help—for a while the Browns' Von der Ahe was Mark Cuban, George Steinbrenner, and the Turkmenbashi all rolled up into one thick German accent. Here are some of the things Von der Ahe did while pacing the AA in attendance: Build himself an enormous statue in front of the ballpark doors; construct an amusement park, with horse racing and an artificial lake, just past the outfield; get arrested in Pittsburgh at the request of a pitcher who'd received a legal judgment against him; and, intermittently, install himself as interim manager, despite knowing almost nothing about the sport, or sports.
Von der Ahe had made his fortune on cheap tickets and expensive beer, but a series of mostly unrelated legal entanglements after the move to the NL turned the St. Louis Browns, four-time AA champions, into second division stalwarts almost overnight. Charlie Comiskey, their field manager in the Association, left for Cincinnati before 1892; he was replaced by a series of ineffectual and temporary player managers, including Bob Caruthers, who returned in 1892 a still-formidable hitter, a dead-armed pitcher, and an undercooked leader of men. To be the greatest Cardinal of this period, between the Browns of the American Association and the Cardinals, borne of a luckily more euphoniously named shade of red than Maroon in 1900, is to be damned with faint praise. But somebody needs to be. Your top hitters between 1892 and 1899:
It's not a beautiful list, but the top position player in this time of considerable upheaval and mediocrity is Roger Connor, chiefly remembered today for being the man whose 138 career home runs were the MLB record for several years until some other guy broke it. Most famously a New York Giant—his 6'3" frame supposedly inspired the name—Connor had played since 1880, and St. Louis was his last stop. 36 in 1894, he put together two outstanding seasons and one ominous adequate one before retiring midway through 1897. (The other interesting name on the list, Lave Cross, played for twenty years from 1887-1907, which is about a hundred and fifty seasons in twentieth century years.) Hopefully the pitching ranks can give us a more inspiring champion for this time period, which the Cardinals would somehow rather claim than the Browns of the 1880s.
Well, no. I'll say this for Ted Breitenstein: It's not his fault. (I'm considering sponsoring his Baseball-Reference page with that motto.) I'm hard-pressed to name the second-to-last man to lose 30 games in a season as spokesman for his generation, but these teams couldn't hit, they couldn't play defense, and on days when he wasn't on the mound (or in the box, as Breitenstein began his career just before the pitcher's box disappeared and the battery distance was settled at 60 feet six inches) they couldn't usually pitch. One year their second best pitcher was Dad Clarkson, inexplicably nicknamed younger brother of John, the most dominating pitcher of the 1880s. I can't fault a guy for struggling when Mike Maddux is of paramount importance to his team's success.
Pink Hawley was a teenager who adjusted to the new pitching distance the year after the Browns traded him for nothing much and cash considerations; Kid Gleason, another guy whose dead arm eventually forced him to the outfield, is best remembered for being the manager of the 1919 White Sox.
It is with some reservations, and a tip of the goofy-looking cap to Ted Breitenstein, who played for a terrible team in one of the worst possible times to be a young pitcher, that I give this contest, such as it was, to Roger Connor. Connor was an excellent player, one of the best hitters of the 1880s, and sheer inertia was enough to make him the best Cardinal of the 1890s.
In 1898 Von der Ahe's ballpark burned down; in the years before permanent concrete ballparks this was the equivalent of the modern-day acrimonious divorce team sell-off, and as if to make matters worse for Der Boss, he happened to have an acrimonious divorce going on at the same time. After years of declining revenues, Chris Von der Ahe, bankrupt, sold out of the franchise he had built from scratch.
Frank and Stanley Robison, sensing an opportunity, took over; the Browns had been dead weight for years, but the brothers had an advantage over Von der Ahe: they owned another team, filled with useful players. It's a good thing they preferred St. Louis, because the other team had the great misfortune of being the Cleveland Spiders.