Hamilton's been hurting every since F1 switched to Pirellis which suit Button's driving style perfectly. Without the switch from Bridgestone to Pirelli Hamilton would still be on top. I think it's pretty much as simple as that.
Have any other drivers been similarily affected by this switch?
Massa or Webber, perhaps, now that I think of it although Webber's change in form from 10 to 11 could just as easily be due to the EBD. We will see this year.
No doubt there will be another change to tyre supplier or specification in a few years. Perhaps they will suit Lewis better.