"the Homeland Security Department and Office of the Director of National Intelligence released a joint statement that said, "The U.S. Intelligence Community (USIC) is confident that the Russian Government directed the recent compromises of emails from U.S. persons and institutions, including from U.S. political organizations."

Parsing sentences from this administration is difficult.  You have to consider what was not said as well as what was said.
The statement from Clapper and Jeh did not specify that all 17 agencies were included in their comment. They are counting on people to not dig any deeper.   Both have been found with being hazy on the facts in the past. Think about this; why would the Dept of Energy, the DEA, and the Coast Guard intelligence agencies even be  interested in investigating a hacking into the DNC?  For that matter, why does the DOE even have one?

In her own immortal words, it takes a "willful suspension of disbelief" to not be skeptical of this statement.