The increasing mix of website traffic coming from Google paid ads relative to unpaid search helps explain the decline in Expedia's profits, but it is not the full story.

Several expenses in the company's income statement grew as fast as or faster than revenue. While marketing costs might be the largest line item, inflation in the cost of revenue and technology spending are not helping Expedia become a more profitable company.

Related: As Google moves further into travel, Expedia calls for level playing field in search results