Third Base - Hector Cruz: -3.4 WAR
It is tough to still around long enough in baseball to put up -3.4 rWAR, but Hector Cruz pulled it off in 1,032 plate appearances from 1973-1977. During his time in St. Louis, Crus slashed just .224/.294/.338 and his defensive marks were somehow worse than that. Cruz would manage to stick in the big leagues with a few different teams until 1982.
In second place, we have another negative WAR recipient in Ken Reitz with -1.8 rWAR from 1972-1980 which is a reminder that third base was a truly terrible place on the Cardinals' roster for most of the 1970's. Fred Hartman returns the rankings to the positive WAR column with 0.6 rWAR during the turn of the century.
Left Field - George Barclay: -1.6 WAR
The negative WAR parade continues with George Barclay who posted -1.6 rWAR from 1902-1904. While his .603 OPS in 1434 plate appearances is obviously not great, he did at least steal 56 base for the Cardinals to go along with his four total home runs. One can only assume that the modern day Athletics would trade one of their better players for him if Barclay was playing today.
The silver medal goes to Charlie James for his -1.1 rWAR from 1960-1964 thanks in large part to his inability to draw walks. Joe Delahanty comes in third place with 1.0 rWAR from 1907-1909 while he slashed .238/.301/.315. Fun fact: Chris Duncan did get into the top/bottom five in left field at 2.8 rWAR from 2005 to 2009.