Currently in the fourth year the wow factor of the Xbox360 in terms of forward movement with their exclusive titles hasn't been as strong and that's something that can hurt them in the long run especially when Sony has proved they have the upper hand with the power of the PS3.
2009 may very well have been a time for Xbox360 to restructure because 2010 seems to be turning out to be the exact opposite in terms of game quality, and the answer is the X-Engine.