Trouble with vertex based tiling/uv mapping

See screenshots: http://puu.sh/j43uZ/971d7383bd.png
http://puu.sh/j440b/2629c54aac.png

Bottom right you'll see the applied texture. The UV map of the center vertex was set to 0.5, 0.5, creating an oblong gem-like shape. What I'm shootin' for is something like this:
http://puu.sh/j44bO/3c3557b712.jpg

I viewed the wireframe for the terrain in WC3 world editor and it's the same as I have set up.. http://puu.sh/j44oV/b7d5350d91.png but somehow it's able to apply non-distorted textures to vertices without the oblong shape.

I'm not sure how I could achieve this, hoping somebody here could point me in the direction.