As far as I'm aware, there are no punishment for missing an attack. In this post's image, when 2 mechs are 2 tiles away diagonally, there are little incentive to get into melee range. You can just stand your ground and spam attacks without repercussion. It's a win-tie scenario where if your opponent walked into your attack, you win, and if they walked to the side of your attack, its a 50/50.
My suggestion: when missing an attack, the attacker suffer the staggered effect (or something like it) to give the player that baited the attack initiative.