Darlington took 3-19 in the Thunder's 12-run win over Brisbane, as the Heat capitulated from 4-119 to 131 all out on Thursday night.

Just 18, Darlington is one of four Thunder players aged 21 or younger who will take on the far-more experienced Melbourne Stars on Saturday.

But she looked every bit the veteran against the two-defending champion Heat, executing two perfect yorkers to claim wickets in a decisive 18th over.

"I've been lucky to play in a couple of high-pressure matches and under-age cricket, some tours overseas as well," Darlington said.

"So we are calling on that experience ...but I think we can also gain experience off Heather Knight and Rachael Haynes in our team.

"It's a really good position for us young players to learn off."

NSW's ability to bring elite youngsters through their successful junior system has for a long time helped the Thunder enjoy a rich development base.

Of the team they take to North Sydney on Saturday night, only Rachael Haynes has played in a WBBL final before while Sam Bates missed the WBBL01 decider with a broken arm.

But as Darlington points out, the team's junior success has them ready for the big occasions.

Avoiding second-year syndrome has also been firmly on their mind after a warning from NSW Breakers coach Dominic Thornley.

While Rachel Trenaman and Tahlia Wilson are in their first full seasons as youngsters, Darlington was the club's player of the year last summer.

She backed that up with 18 scalps this season, while 17-year-old Phoebe Litchfield has the highest batting average of all teens in the tournament with 173 runs at 28.83.

"It was something we spoke about," Litchfield told AAP.

"I have had added pressures and expectations. It's been a little more difficult but the team has guided me through that.

"It's up to yourself to develop new areas of your game."

Saturday night's final won't be broadcast on Seven Network's main channel, instead put on 7mate.

There had been some thought the game would be shown by Seven into both the Melbourne and Sydney markets with the Stars and Thunder playing.

Ratings numbers have risen almost 30 per cent on last year's semi-finals, with 299,000 tuning into Thursday night's game on Seven and Foxtel.

That saw it out-rate a cricket version of The Front Bar in the Sydney and Brisbane markets, which was shown on Seven's main channel.

However, Seven insist that they see little difference between their channels, with Frozen on the main digital channel and the the WBBL on 7mate.

It comes after Nine Network was criticised earlier this year for broadcasting the women's T20 World Cup final on secondary channel GEM.

Australian Associated Press