Ah yes, Lord Hill, the UK's new EU Commissioner. The New Statesman sets out the problem:
Including President Juncker, there will be some 28 Commissioners, one from each of the member states. The difficulty lies in the fact that, given the Commssion's relatively restricted range of responsibilities, there are only between ten and fifteen worthwhile portfolios for allocation. In an ideal world, therefore, there would only be ten to fifteen Commissioners. But we have 28 and, as all the Commissioners are regarded as equal, each must have his own bailiwick; there can be no question of having a senior and a junior Commissioner working together on the same portfolio.
The current responsibilities of Commissioners are set out here. Some of these posts are clearly sinecures, such as Digital Agenda, Research, Health, and Consumer Policy, where the Commission simply has very few functions to fulfil. But, as each Commissioner must have his or her own Directorate-General, the number of directorates-general expands to match the number of Commissioners.
Crazy, yes, but that's the way it is. And of course each of the member states looks to gain a plum job for its own Commissioner. In these circumstances, never mind Cameron's three favoured portfolios - Lord Hill will be doing well just to get one of the portfolios with real content.