Here's why:
* Common nouns refer to general categories of people, places, things, or ideas. They are not capitalized unless they are at the beginning of a sentence or part of a proper noun.
* Proper nouns are specific names of people, places, or things. They are always capitalized.
Since "cricket" refers to the sport in general, it's a common noun.
Examples:
* Common noun: I love to watch cricket matches.
* Proper noun: Did you watch the India vs. Australia cricket match?