At Winthrop University, we are fortunate to have a great P.A. Announcer, Mike Markham. He is knowledgeable of the game, keeps the fans involved, and is very professional. He has been announcing our matches for a number of years and asked me the difference between the libero and defensive specialist. Its interesting to have a person with the experience of Mike, not clear on positional roles and it is our responsibility of the volleyball world to educate our fans. The more educated our fans, the more likely they will get hooked on volleyball.
The libero can be a confusing position for those that are not familiar with the game and it is our duty to explain it. Here is my description to Mike about the difference between the libero and defensive specialist (D/S):
The libero is the player on the court in the different color jersey. The libero can only play back-row and cannot jump and attack (technically, the contact of the entire ball cannot be above the top of the net) . That player can substitute for any player on the court that is in the back row without it counting against the teams 12 allotted substitutions. The libero must sit out for one play before they return in for another player. That is why you see the libero come in and out (most often for the middle hitter) and sit down for a play before re-entering the game. The libero is allowed to serve for one player, and only one player, on the court.
A defensive specialist (D/S) is a player that substitutes in for any player. Theoretically, the D/S can play any position on the court, including front row. The D/S can attack (front-row or back-row, behind the 10 foot/3 meter line). A player is considered a D/S because they usually substitute in for less skilled back-row player that is rotating from the front row into the back row. The substitution counts against the team’s 12 substitutions. Each time this D/S substitutes in, it counts as one substitution. When the D/S rotates through all three positions in the back row, the front row player will substitute in for the D/S. This substitution also counts as one substitution. The libero and defensive specialist can be on the court at the same time.
Sometimes I wish the game was more fan friendly in this way, but then I look at sports like football and all their positions and rules, and know volleyball just needs to spread through education...here in the United States. But then again, football is not nearly as popular as volleyball across the world. Maybe football should take a few lessons from volleyball.