Catcher - Jack Boyle: 1.2 WAR
Taking the top/bottom spot at the catcher position is Jack Boyle who played for St. Louis from 1887-1889. You are forgiven if you don't remember his illustrious -0.4 rWAR 13 year MLB career. He hit a total of 11 home runs for the Cardinals with a .618 OPS in 1510 plate appearances. "Honest Jack" was actually pretty well regarded for his fielding, so one wonders if he would be appreciated more if there was better data available for him.
Mike Matheny actually made a real run at the catcher spot for his tenure with the Cardinals from 2000-2004 as he managed just 1.6 rWAR to come in second place. Hal Smith and Bill Sarni tied for third with 2.0 rWAR and both of them caught for the Cardinals in the 1950's.
First Base - Nippy Jones: -1.3 WAR
Getting the "honor" at first base is Nippy Jones with his -1.3 rWAR from 1946 to 1951. Despite having a very funny name for a baseball player, Nippy was decidedly unproductive player with just 22 homers and four stolen bases across over 1,300 plate appearances for St. Louis. To the surprise of no one, Jones did not play much in the big leagues after he left St. Louis, although he did work his way back to the big leagues and managed to help the Braves win a World Series game after successfully showing the home plate umpire shoe polish on the ball that he argued hit him in the foot.
Gene Paulette took home third place, who was a Cardinals' first baseman from 1917-1919 and barely qualified for this list at 1022 plate appearances, with 1.7 rWAR Tino Martinez and Matt Adams rounded out the top/bottom five which is somewhat surprising.