1. Rogers Hornsby
Choosing the best second baseman in Cardinals history is kind of like the Capital One commercials in which the schoolyard basketball captain selects Charles Barkley or the rock band picks Slash as their new guitarist. The Rajah is far and away the greatest player ever to man the keystone for the Redbirds.
Roger Hornsby was a Cardinal for the first dozen seasons of his career, during which time he produced a stunning triple-slash line of .359/.427/.570 over more than 1,500 games for a 178 OPS+. He smashed 191 home runs, drove in 1051 runs, scored 1080 times, and walked much more often than he struck out, with 648 free passes compared to 474 whiffs.
Sure, it was a different game a century ago, but Hornsby clearly was one of the best players of his time. He captured an MVP award in 1925 after being the runner-up in 1924. The Rajah also led the National League in batting average six times (1920-1925) - including a stunning .424 mark in 1924 - on-base percentage those same six seasons, and slugging percentage and OPS those same those half-dozen years plus 1917.
In addition to those rate stats, Hornsby was first in RBI, doubles, and hits four times - with a major league-record 250 in 1922 - and runs scored three times during his Cardinals tenure. He was a league leader several more times in these categories after leaving St. Louis. For those interested in WAR, Hornsby had 90.8 bWAR for the Cardinals, a stunning average of 7.6 per season.
Whether you prefer accumulated numbers, rate stats, or the more modern perspective of WAR, the statistics above more than make the case that Hall of Famer Rogers Hornsby clearly was the best second baseman ever to wear a St. Louis Cardinals uniform.