That's exactly what Midrange means.
Midrange means that you still play the early and midrange curve cards and against control decks you play aggressively to kill them fast. That means Bloodlust, Rag, Lightning Bolts to face, Spirit Claws to face.. whatever way you can to kill them fast because you don't win against them by out controlling them.
Against faster decks you control them and keep them off the board.
Game has so few control decks that most of the time as Midrange Shaman you are just trying to control the other degenerate decks from getting out of control and then tempo them out with your threats. Trust me when I say that when I play my Renolock against a Midrange Shaman, there's no controlling going on the Shamans' part (outside of Hexing massive taunts) he's trying to play it like an aggro deck... which is what he should be doing because it's a Midrange deck and he can't win against Renolock in the late game.
There is actually a Control Shaman deck and it's not that bad. It uses Elemental Destruction, Healing Wave, Lava Shock, Hallzeal, Earth Elementals even Bog Creepers to get into the late game. It plays significantly differently from Midrange Shaman because it actually wants to go into the late game.