Hey there,
Yes, this can happen. Not all games respond to an OC the same way. Although generally speaking it should be an increase for the most part.
The only time that it would really be a loss, is if the OC isn't stable, or as mentioned a particular game engine may not respond to the OC.
You have some aggressive OC on the core, not so much on the ram, but still high enough. Maybe try lower settings and see how the games respond, and try and hit a sweetspot.