The map changes in patch 7.20 nerfed creep pulling for dire.
The specific problem is pulling through to the hard camp, because the hard camp resets too soon and/or the small camp i too far away. (See image1, the area marked Hard is where the hard camp resets)
There is also another unfair advantage the radiant has over dire. On the radiant safe-lane you can pull the hard camp into the lane by cutting down a single tree, something that isn't possible on the dire side.
My suggestion to solve this imbalance is to move the dire hardcamp up to where the obelisk currenly is placed and block a direct pull into the dire side of the lane with trees but still allowing it to be pulled into the lane if a tree is cut. (See image2 for a rough outline)

Image1: http://i.imgur.com/5WmJg42.jpg
Image2: http://i.imgur.com/oALN9ef.jpg