They tweaked the ratings here and there so that they could allocate the money they wanted, rather than the amounts the system churned out from its rigid distribution.
All systems are open to a degree of honest playing (as opposed to out-and-out fraud). The most obvious example is tactical voting where individuals don't vote for their preferred candidate but for one who is more likely to keep a hated candidate out.
In their book, When to Rob a Bank, the Freakonomics people play around with the idea of being able to buy as many votes you like in an election (a bit like on X-Factor). They point out the negatives - people with lots of money could strongly influence the election, you could buy someone else's vote etc. - but also some of the positives. However, there's no doubt that the opportunity to a purchase a vote, even if it's a single one, really does open the door to playing the system.
I think that's interesting, because that's effectively what the Labour Party has done for its upcoming leadership election. By just paying £3 to become a 'registered supporter' you get a vote in the election. Usually this would be a little 'so what', but at the moment Jeremy Corbyn is looking as if he could have a chance of winning. Corbyn is an interesting candidate in that he is probably the most likeable individual with a genuine passion for his ideas. Yet if he won the leadership he would pretty much guarantee that Labour would lose the next general election, because his ideas are too radical for the country at large.
This being the case, if Conservative voters understood numbers, they would be signing up in their droves to become registered supporters so they could cast a vote for Corbyn. Just £3 for the opportunity to push the alternative party out of reach of government. Sounds attractive doesn't it? Admittedly they would have swallow their honesty and click Next on the agreement above, but they probably would be able to do that. Rather worryingly, the screen that follows says you are signing up for the chance to choose the Mayoral candidate for London, but I assume that's a technical blip (I've reported it and will let you know how Labour respond).
Of course, this could be really clever gamespersonship on the part of the Labour Party. If this happened they would swell their party funds with cash from Conservatives - if they had some way of knowing that Corbyn won't win the final vote, they too could be playing the system. But assuming that's not the case, Tories - who amongst you is a player?
P.S. I heard after I wrote this that the Daily Telegraph has apparently suggested something similar, but I was not aware of that at the time of writing.