Two-strike pitching from the staff
How many times have the Cardinals had opposing players in two-strike counts, and then they ended up doing damage against them? Feels like a lot, right? Well, that's why the Cardinals rank 30th in baseball in opponents batting overage with two strikes, which is sitting at .210, which is 12 points higher than the 29th-ranked Athletics.
They've given up the 5th-most home runs in two-strike counts, walked the 5th most batters, and surprisingly struck out the 15th most in those situations. St. Louis just can't seem to put away batters, which prolongs innings, and eventually leads to really bad results.
The lack of strike-out stuff, the absence of top-end pitching talent in the rotation, the strain on the bullpen, and the need for more quality arms in it have all contributed to that problem.
Honestly, we could name so many more issues with the Cardinals this year, but these eight seem to stand out as some of the biggest reasons they are where they are.