Image source: Zynga.

Do you remember when Zynga (ZNGA) was valued at nearly $11 billion? The social game maker has fallen quite a bit since those days, after the hype around its popular but ultimately transitory games quickly faded. These days, Zynga fetches a market cap of just $1.7 billion.

Shares got crushed last week following a disappointing earnings release, which begs the question: How long can Zynga keep fleecing its current player base?

Calling all players
Make no mistake. Zynga's player base is shrinking, and fast. But at the same time, Zynga has been able to significantly improve monetization among these daily active users, or DAUs. They keep coming back for more, even if they are in fewer numbers. Average bookings per DAU continues to march higher, hitting a new record of $0.11.

Data source: SEC filings.

But the DAU base has fallen from 28 million in Q1 2014 to just 18 million last quarter. Average monthly unique payers, or MUPs, have also declined. Last quarter, there were only 800,000 MUPs, down from 1 million a year ago. That's about 1.7% of the monthly unique user base right now.

Winner, winner, chicken dinner
Zynga is doubling down on its move toward live mobile franchise titles that resemble popular gambling games. The trio of titles that make up Zynga's "core live mobile franchises" -- Slots, Words With Friends, and Poker -- saw bookings jump 63% throughout 2015. These types of games have the same addictive qualities as their real-money counterparts. It's kind of like going to the bar and buying in to the poker game that's for "entertainment only."

Eventually, players realize that it's a raw deal and stop playing, though. This is precisely what's happening to Zynga. While it is currently quite successful at getting players to purchase increasing amounts of virtual goods, the writing is on the wall unless Zynga can turn around its user metrics.

In an interview with GamesBeat, CEO Mark Pincus attributed the decline to tough comparisons from last year due to new game launches. Pincus then pointed to said core live mobile franchises that saw DAUs increase by 1%. According to Pincus, the turnaround is on track.

The house doesn't always win
For now, Zynga can fend off fundamental deterioration since gains in one metric are helping to offset losses in another. Total bookings were effectively flat year over year at $182 million.

But farther down the income statement, the cracks are starting to show. Adjusted EBITDA fell significantly to just $1.7 million. Zynga lost a little bit more too on a GAAP basis, even as its adjusted numbers improved. Eventually, Zynga's luck with its players will run out.