Really do have to wonder, as Hamilton certainly does seem to be the fastest Mercedes driver across the Mercedes teams. If his engines are the only ones giving way, is there something in his driving style which is overstressing components without being clear on telemetry.
Although he might have felt yesterday was terrible in luck terms, it wasn't as bad as it could have been, if Vettel had not swiped Rosberg, then Hamilton would still have blown up, and Rosberg would have taken all the points.
I still fully expect Hamilton to win the championship. Five races is plenty for him.
His reliability was mostly fine for the two previous years and his style has not changed, so it's not that.
When you take into account he's already taken a penalty for new engines and now only has two remaining for five races it's pretty bad,
He may have to miss out practice seasons to make them last and that's a lot of valuable data drivers need during the race and qualifying.