First-line managers who have to deliver against HR policies like this have my every sympathy. I was made a manager in a certain very large IT company. I managed a team of mixed fixed-term contractors, contractors and permanent staff. My manager came to me at the start of the new year to tell me that during the upcoming staff performance review, I had to make 15% of my permanent staff a 1 performer, 75% a 2 performer, and 10% a three performer. When I complained that I didn't have enough permanent staff of a low caliber (c'mon now, I was doing the hiring!), I was quite neatly told that if I couldn't make up the numbers from my workforce, then it would be OK as from his level he would meet his overall target for 3 performers by making ME one.
Actually, that's what ended up happening, not that any of my workforce found out about that 'deal'. I lasted a further four years of management in increasingly Kafka-esque circumstances until I decided that I should stop trying to rise up the ranks of management, give up and go back to being a techie. I've never regretted the decision, and I can sleep at night.