Detail and ClarityEdit
Perhaps the best way to look at it is to think of the battle as a game of chess, only played by words rather than by movement. Or, more accurately, it's like a game of chess over the phone, where each player has a board set up, moving each piece and then telling his opponent what the move was while his opponent then moves the piece on his own board to match. Each player's description of the move must be precise, detailed, otherwise the opponent will not be able to respond properly. Imagine telling an opponent simply "I moved one of my knights"! Such a description is useless unless the player at the other end is also told which knight was moved, where it started from, and where it was moved to.
As an RP example, think of two players facing off, both of them using a sword in each hand. The first player to make a move could be vague about the move, saying:
I raise my sword and slash at my opponent's chest
This, however, causes problems. Among other things, the attacker has two weapons, but only posts using one, leaving no clue as to which one he attacked with, how deep the slash is intended to be, whether it is aimed high or low, what motions his arm is going through to get there, how close he is to begin with...you get the idea. The defender, as a result, has to interpret that in whatever way makes the most sense to her--which may or may not be remotely close to what the attacker intended. As a result, the mental "picture" each fighter has of what's going on starts to become radically different.
Rewind. Instead of the vague statement from earlier, this time the attacker says:
I lift the sword in my right hand. Stepping forward quickly, I bring it across from right to left in a slash at my opponent's chest, three inches below the collarbone, before stepping back.
This time the defender knows exactly what's happening, and can respond appropriately.