The New Zealander confessed that his team found it difficult to gain a foothold in the match after spending the first 20 minutes under the cosh.
"We set ourselves up in the first quarter as our kicking was aimless and our discipline killed us," BBC Sport quotes Blackadder as saying.
"We were on the back foot for the whole of the first 20 minutes and didn't have any possession at all.
"We prepared well but they executed better and we didn't play the game, we said we would."
The result saw Exeter lift the trophy for only the second time in their history.