In team sports, there are more players on the team than can play at any one time. The best players are the ones who play at the beginning - the "start" - of the game. (This group of players is also referred to as the "first string".) In your example, last year the player was not one of the starters so he sat on the "bench" while the starters played. Later in the game, he would come "off the bench" and be put into the game to replace one of the starters. (Your example also tells us that he was one of the better "second string" players, since he was one of the first players to come off the bench during a game.) It is expected that this year he is now a better player and will become one of the "starters".