A revamped and expanded finals series is the last hope for broadcasters to wring some quantifiable upside out of this summer's Big Bash League, after its traditional television audience declined for the fifth summer in a row.

While the BBL remains among the most watched domestic leagues in Australian sport alongside the AFL and NRL, its audiences on free-to-air and subscription television have continued a significant drop, although this has been partly offset by the growth of the streaming service Kayo, which has grown to more than 450,000 subscribers since its launch in November 2018.

According to OzTam figures obtained by ESPNcricinfo, the five city metro average audience for the BBL on free-to-air Seven has diminished from 424,000 last summer to 384,000 this season, after the league returned an average audience of 649,000 in its final summer exclusively on Ten in 2017-18 - in itself a mild decline from the peak of 759,000 in 2015-16. The national average audience, including regional viewers, stands at 611,000, down from 638,000 in 2018-19, and 944,000 in 2017-18.

Fox Cricket's audiences have also gone down somewhat, to an average of 158,000 viewers nationally this season from 211,000 last summer for exclusive games, and to 169,000 for games simulcast with Seven, as opposed to 200,000 in 2018-19. A significant portion of Fox Cricket's exclusive games have been afternoon fixtures further contributing to the downturn. Having also experienced a reduction in broadcast audiences for international cricket this season, the head of Fox Sports Pete Campbell had told the Sydney Morning Herald that those figures were in line with projections as more sports watchers migrated to the cheaper Kayo service.

Speaking during the SCG Test earlier this month, Cricket Australia chief executive Kevin Roberts said on SEN radio that in a landscape where there were challenges across all forms of TV viewership cricket "is trending well ahead of the broader trend."

Aggregate average national audiences for Seven and Fox Cricket across the regular BBL season duly tally up to 780,000, down from 838,000 in 2018-19, and a long way short of the 944,000 returned by Ten three summers ago. This comes after a raft of changes were made between seasons to make the tournament friendlier to broadcast audiences.

These included the advent of strategic time outs, greater use of players being on the microphone in-game, a more condensed schedule with more days of double headers, the recruitment of the high profile star AB de Villiers to the Brisbane Heat, and an improvement in the standards of pitches being prepared.

That last adjustment reaped a significant boost to the runs scored in the BBL this season - as of the end of the regular season the average run rate had gone from 7.82 to 8.17 - an area frequently cited by broadcasters as a way of drawing back larger broadcast audiences. However, the need for more afternoon fixtures in a tighter schedule has had a sapping effect on crowds at the grounds and also television audiences at home. The expansion of the finals series, including a fifth team and also enhancing the incentives to finish at the top of the table, was another change pushed for strongly by the broadcasters.

"In all our discussions with our partners they've been really happy with how we've worked really closely with them to optimise the season," the head of the BBL Alistair Dobson said earlier this week. "Their audiences have been strong, they're really excited about the finals series and I think you've seen both our partners really lean in to the promotion and support of the new finals series, they've really loved the accessibility of the players we've had in the competition."

One of the areas in which the BBL's decision-makers will soon need to make a call is how sustainably they can continue to run the tournament on the basis of only one game ever happening at once. In the rival AFL and NRL competitions, it is common for at least two matches to run simultaneously, particularly in fan-friendly Saturday night and Sunday afternoon time slots, to maximise opportunities for attendance at the ground. This move, of course, would result in a splitting of the national broadcast audience.

"There's certainly some discussion around whether there's other ways to put games up against each other," Dobson said. "Whether they're double header afternoon and night games, whether there's the night games into the Perth game, so there's lots of different opportunities and different ways we can structure the season. Once we get through this year, we'll have a close look at it.

"Next year's BBL10, so that's a milestone year. What it looks like in BBL15, BBL20, is really front of mind at the moment as you complete 10 seasons of the competition and it's really entrenched now as part of the Australian summer."

The move to a 14-game home and away season for all clubs was a key plank of Cricket Australia's A$1.18 billion broadcast deal with Fox and Seven in 2018, helping to bring the BBL's value up to around half of the total package, where during the 2013-2018 deal with the Nine and Ten networks it had been worth only around A$100 million. A turnaround in broadcast audience figures will be critical for CA's ability to ask for similar figures next time around.

"We had over one million people come to a BBL game, which is a phenomenal response from cricket fans around Australia," Dobson said. "We're happy with where we got to with attendances, but that said, making sure the game stays as appealing and attractive and entertaining as possible is almost our No. 1 priority. So how do we make sure we ensure that in the next 10 [years], people are still coming."