From BR Bullpen

Groundskeeping refers to the preparation and upkeep of the playing field and associated facilities. The details of groundskeeping can affect the playing characteristics of a field as much as the field's basic layout, so the task is considered to be an important one. Groundskeeping is generally carried out by a staff of groundskeepers who report to a head groundskeeper.

Many different groundskeeping factors can influence the playing characteristics of the ballpark. Some of the most important include:

  • Turf type and length. The turf affects the speed of rolling baseballs, which affects the way that fielders must play. Fast rolling balls are more likely to roll past a fielder, resulting in either a single if it rolls past an infielder or an extra base hit if it passes an outfielder. The speed of a grass surface depends on how it's cut; the shorter the grass the faster it plays. Astroturf is a very fast playing surface, while more modern artificial surfaces play more like grass.
  • Surface evenness. Balls that hit an irregularity in the playing surface, such as a rock, dirt clod, tuft of grass, or seam in an artificial surface, will bounce unpredictably, making the fielders' job more difficult.
  • Ground hardness. A hard playing surface will cause the ball to bounce higher. This tends to produce a faster playing surface, since bouncing balls are slowed less than rolling ones. On a very hard surface, a Baltimore chop can bounce so high that the batter can reach first base before the ball comes back down.
  • Ground levelness. The level of the ground near the first and third base lines is especially important. If the base line is raised slightly above the level of fair territory, bunts will tend to stay fair, and if it's lowered slightly they'll tend to roll foul. This can have an important impact on a team that bunts a lot.