Through Game 27 of the 2017 home schedule, the Rays averaged 15,089. Here is how that average attendance compares to other years.
Interestingly, this was the earliest the Rays reached game 27 in over 10 years. It is also the only time the Rays averaged in the 15,000s. 2017's Game 27 attendance is the 3rd lowest since 2007, topping only 2007 and 2015.
Since 2009, Rays final average attendance has been with 5% of their 2017 average attendance. Only 2007 and 2008 are outstanding from this observation.
The following graph depicts the above chart:
Outside of 2007 and 2015, every time the Rays had a positive gain in attendance, they made the playoffs. Which makes sense as September attendance is highly correlated with playoff potential. If the Rays aren't in contention, Florida sports fans are possibly more likely to tune in to college football or the NFL.
But what makes 2007 and 2015 unique and could 2017 fall into this category? Possibly yes, but I wouldn't be surprised to see no.
In 2007 and 2015, the Tampa Bay Lightning made the NHL Playoffs. I have written several times how Lightning playoffs suppress Rays attendance due to local fan money and time expended on hockey.
With Lightning hockey not an impact for the 2017 Rays home schedule, the team won't see the returning of fans from hockey. They've had the season to themselves yet barely drawn above seasons in which there were other events to occupy local sports fans.
If I were to predict, which I try not to do too often, I would say Rays final average attendance will be between 15,000 and 17,000 in 2017. If the team stays in Wild Card contention - which is possible - they could draw fans to meaningful September baseball.
That would make all the difference.