You get frost nova at, what, level five?
On Crucible, a tower rook can prevent you getting to level five until he is level 7+ at the least. A tower rook controls the lane extremely well, and his immobility doesn't matter when you consider that there is only one thing of interest on the entire map for him to park himself.
Sure, you can stun the towers; it would work wonders in theory! But in practice, on Crucible he will out level you enough to where he can probably fight you without his towers. On other maps, yeah, Rook is easy. But Crucible is a shit map with one lane that Rook can keep until his enemies hit mid-high levels, and by that time he outlevels and cashes them easily.
