The Scots were unable to back up their two previous victories over Italy and Ireland with another over Danny Wilson's side as they were downed 42-17 in Inverness on Friday night despite leading 10-3.
Scotland were perhaps the architects of their own downfall however as they presented their opponents with multiple try-scoring opportunities through defensive mistakes and misplaced passes.
And the former Scotland international insists he must see improvements in the final game against France.
"We were second best in everything [against Wales]. Wales were very good, but they scored every time from our possession. That is hard to take," said Lineen.
"The players emptied themselves in the last two matches, but they didn't [against Wales]. However, we have to take this loss on the chin and finish with a good performance against France next week."