Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.

### Instruction:
Read the given paragraph and find the main theme

### Input:
In baseball, home-run hitting has been much more difficult in the past few decades, due to the ball being harder, as well as the transformation of stadiums after 1988 to favor pitching.

### Response:
The main theme of the paragraph is that hitting home runs has become more difficult in recent years because of the changes in the ball and stadium design.