There are many variables which can affect your score in the game.

[Distance]
The further the ball flies, more points will be posted.

[Hit Accuracy]
Higher accuracy hits will award extra points as per below:
MISS - 0pts
BAD - 0pts
GOOD - 10pts
GREAT - 40pts
PERFECT - 80pts
CRITICAL - 120pts

[Home Run Score, Combo Score]
Successful home runs will awawrd 20 extra points.
If you manage to continue a streak of succesive home runs, additional 20 points will continue to stack.

[Scoreboard, Skill OBJ, Symbol, Pole Hit Bonuses]
Hitting one of these 'objects' found in each stadium will award bonus points.
Scoreboard - 100pts
Skill OBJ - 150pts
Symbol (Statues, Figurines) - 200pts
Pole (Foul-ball marker) - 250pts

["Cycling" Home Runs]
Scoring home runs in each direction (left, center, right fields), will result in a "Cycling" home run.
Cycling Home Runs award 300 extra points.

Also, Legendary grade batters can hit the ball to the same direction repetitively when attempting Cycling Home Runs.
The more cumulative number of home runs (Maximum of 3 per direction) you hit, the higher score you will get.

[Announced Home Run Score]
Successfully hitting an Announced Home Run grants an extra 500 points.
An Announced Home Run is triggered in a random direction when the Announced Home Run Gauge is full.
The Announced Home Run Gauge fills up faster when your batter earns higher accuracy points.

Additionally, Legendary batters may fill up the Announced Home Run Gauge at a slower rate,
but they earn an extra 800 points when they succeed in the Announced Home Run. (ANNIE MCLANE)

[Skill Effects]
Many equipped cards (batters, gears, skills) have bonus effects that grant additional score when you batter performs a specific action within the match.
Each of these bonuses are explained if you tap on the icon under each card's description.