Runners in scoring position
This has been an issue all year. The Cardinal hitters have failed to capitalize with runners in scoring position. Period.
Similar to meatballs, having runners in scoring position presents a prime opportunity to score runs. Runners being on second and/or third base puts pressure on the defense and pitcher. In many cases this year, the Cardinals have had runners in scoring position with no one out and have failed to take advantage of this opportunity.
The Cardinals rank 27th in all of baseball in batting average (.222), 29th in OPS (.635), and 28th in BABIP (.259) with runners in scoring position. Typically, hitters perform better in these situations due to the pressure on the opponent, but the Cardinals are actually hitting worse with runners close to scoring.
While there are several parts to a team's negative run differential, not scoring is foremost. Scoring when runners are as close as possible to home plate is vital, and the Cardinals have failed to do that. The Cardinals have left 7.09 runners on base per game, the 5th-worst in the league. A month ago, the Cardinals were one of the worst teams at striking out while a runner was on third and there were fewer than 2 outs. Even a sacrifice fly would get that runner home, and the hitters couldn't do it.
Taking advantage of easy scoring opportunities will be key for the Cardinals in the second half of the season. The heart of the order must bring home runners like Masyn Winn and Brendan Donovan who reach base often.