Well, that will explain Sonic 06, Sonic and the Secret Rings, Sonic Unleashed, Sonic Colors, Sonic and the Black Knight, Sonic Rivals 2, Sonic and SEGA Allstars Racing (all versions), Sonic The Hedgehog (GBA Version), Sonic Lost World and Sonic Boom.
There's nothing wrong with the Black Knight. Heck, it's one of my favourites. It's just that the idea for the Black Knight seems a bit random for the time. As for Sonic Boom... New Knuckles. Enough said.