And yes, everybody games it. At the end of every half there's a flurry of "brag posts" about everyone's impactful projects. Better braggers get better results. Sometimes the metrics and measurements and analyses are pretty obviously suspect, but who wants to be the one to say so and never get positive feedback on their own review from that person or their friends ever again? Again, it comes down to consensus on whether the claimed improvements are real or not.
I was in infra (storage) so I don't know how it might be different in more product-oriented parts of the company. However, when the fundamental philosophy behind measuring and rewarding impact is questionable that sets an upper limit on how good things can be over there.