The ouya does some weird things with scaling, what I believe it's doing is rendering everything at 1080 then bringing it down for lower resolutions, so when you force the ouya into 720p using side loaded apps it's doing that but it's still producing a 1080p buffer. This is one of the reasons as to why the ouya is so weak feeling, a lot of horsepower goes into the resolution.

the OUYA team would have been best limiting the device to 720p but they wanted to get that 1080 buzz word in there I guess.