Only active players contribute stats toward your team's fantasy totals. An active player is any player occupying a non-bench position. This includes all standard positions (1B, SS, OF, P, RP, etc.) as well as the Utility (Util) position.
Players occupying a bench position on any given day will not record stats that will be added to your fantasy totals.
Once earned by an active player, fantasy stats will never be removed from your team totals, even if a player is later traded, released or moved to a bench position. So, if a player is active on Monday and hits a home run, that HR will remain part of your team totals even if that player is benched for Tuesday's games.
He would not be eligible to earn additional fantasy stats on Tuesday, however.
When viewing your matchup progress in a Head-to-Head league, you may see stats listed next to bench players that are counted as part of your matchup results.
This is because the player was active earlier in the week before being moved to a bench position. In all leagues that utilize daily roster moves and lineup changes, players can be shuffled between bench and active positions as the week progresses.