Addressing delegates at the start of the annual NHS Confederation conference today, Sir William said it was the challenge of NHS boards to determine the right commissioning strategy for their local population.
He said PCT's must be provided with 'real time information' in order to make 'informed' commissioning decisions.
'You need to know what is going to happen tomorrow and the next day, and at the moment the information is normally appallingly bad, stale, and out-of-date,' he added.
Sir William said it was 'very difficult' for PCTs to operate their contracts with the acute sector if the information available to them was three months out of date. 'I have taken this issue up with NHS chief executive David Nicholson because it really is impossible at the moment,' he added.
Speaking at the same session, Department of Health head of primary care Gary Belfield said that over the next six months the government would start to talk about 'world-class commissioning' in PCTs.
'This is about PCTs investing for health and getting more information into the primary care setting and sharing more information between PCTs and local authorities,' he said.