What is "fastballs"

Usage examples of "fastballs".

In the top of the second, Eric Hiljus continues to indulge Yankee hitters with fastballs down the middle of the plate and they strike for four more runs, three on a home run by Derek Jeter.

Twice in the first four innings the Oakland catcher has taken outside fastballs and driven doubles to the opposite field.

Two days ago Grimsley had thrown him six straight sinking fastballs, down and away.