
When coaches refer to making a "switch" at the start of a rally -- as when a middle hitter who starts the rally in left front switches to the middle -- there is no real "footwork." Just run to your position at the earliest opportunity, which for many teams means, "When we serve, switch immediately; when the opponent serves, switch after we attack." Most advanced teams switch immediately, regardless of who serves. While there is no specific footwork for switching, players should have assigned "alleys" for making their switches so they don't run into each other. Most teams give their middle hitter the alley closest to the net, because she needs to be prepared to block before anyone else.
When coaches refers to blocking footwork techniques there are specific footwork patterns that middle blockers should know ...and shuffling like a basketball player is not one of them.
The "whys" first:
The goal of blocking footwork is get two or three blockers (depending on your team's defensive scheme) lined up side-by-side as quickly and as early as possible. Ideally, the block should be "set up" -- meaning, all blockers in position and waiting to jump -- well before the hitter attacks the ball. This allows the blockers time to gather themselves and jump as high as possible. Just as importantly (perhaps more importantly, depending on the level you play), it gives the backrow defenders time to position themselves correctly, usually around the outside of block and in the seam between blockers. Shuffling, because it's slow, rarely gives you enough time to set up the block effectively.
For middle blockers, shuffling footwork is "bad" because it often makes them late for two-man outside blocks, which creates a hole between the outside and middle blocker that is difficult to defend. To close such a hole, some middles attempt to "superman block" by jumping toward the outside blocker rather than jumping straight up, but this technique is injurious as well as ineffective. Shuffling is bad for outside blockers as well, particularly if they try to "check block" the middle before moving outside, because when the opponent does set outside, a shuffling blocker will cause a traffic jam -- that is, she will slow down anyone else who is following her outside to block.
Here are the "hows":
To move along the net effectively and efficiently, blockers should use one of two types of footwork, depending on how far they have to go.
In short, regardless of how far you need to go, your first movement should always be a long, strong step with your "set-side" foot (if the set is to your right, with your right foot; if the set is to your left, with your left foot). If one step is enough, plant both feet and go up hard. If it's not, take one more step before going up to block. You should rarely, if ever, take more than two steps to block.
A couple of other points about blocking: