Thanks to their intelligent data gathering, Valve is able to take a look at gameplay statistics in Counter-Strike: Global Offensive and find trouble spots in various maps. Such was the case when it comes to Cobblestone and Overpass, both of which have been updated in the game's most recent update.

The CS:GO team analyzed the win percentages of the T's vs the CT's and found that Cobblestone is most comparable to Nuke and Overpass is most similar to Dust2. The following charts are from the top four skill groups in competitive matchmaking from December 20, 2013 to January 20, 2014.

They then break down the wins to see exactly how each side achieved victory.

It's thanks to data like this that Valve is able to adjust the maps so that no one side is significantly favored over the other. The CS:GO map data blog entry provides full datasets for all of the skill groups, not just the top four.