The way the data was presented. Instead of restricting it to games Darvish actually pitched in (counting TEX relievers, opposing SP + RP, rough estimate a 3000 pitch sample.) that link measures him against every other strike zone, from every other mlb game he was never a part of.
The Ranger offense is profiting off that strike zone too. A big difference though, Yu can still pitch middle-in and miss bats/get outs while it's rare the opposing pitcher will be able to do the same. How effective would you expect Nelson Cruz to be if an umpire was liberally calling the lower outside corner? Texas stands to lose a lot more than they would gain.