Three True Outcomes
A home run, a walk or a strikeout: at bats the defense never touches.
How it actually works. Every other outcome in baseball is decided partly by where fielders are standing and how well they play. These three are settled between the pitcher and the hitter alone. A hitter whose game is concentrated in them is trading contact for damage and patience, and the share of plate appearances ending this way has climbed steadily for decades.
Why it is done, and when it is wrong. This is not a fashion, it is a response to information. Once teams could measure that a ball hit hard in the air is worth vastly more than a ball hit hard on the ground, and once they could position fielders precisely enough to eat ground balls, the incentive to hit the ball in the air became overwhelming and the strikeouts that come with a steeper swing became an acceptable price. The counter-argument that has real force is not about aesthetics either: a strikeout cannot move a runner, cannot produce an error, and cannot be misplayed, so an offense concentrated in these three outcomes is more volatile inning to inning even when it is better on average.
What people get wrong about it. The pitching side of this is usually left out and it is half the story. Velocity and breaking ball usage have risen at the same time, so some of what looks like hitters choosing to strike out is hitters facing pitches that are harder to hit.
Batter's Eye: look up anything in baseball