Tierney spelt out a stark picture of the game in Wales, admitting “so many parts of the system are broken” and admitting the product on offer to fans was “not good enough”.
Former Wales captain Sam Warburton said Welsh rugby must now seriously consider cutting a region to pool the player talent into three clubs.
But Tierney responded by claiming that process would take at least two years as well as creating “distraction and pain” and believes keeping Cardiff, Dragons, Ospreys and Scarlets is a “bold” decision.
“We are absolutely committed to four regions equally, giving them all the chance to be successful and that will grow the game,” she said.
“We are increasing the funding as well as improving the pathways to have enough quality players to service them and working on the commercial side.
“That strategy will be quicker, faster and have an impact sooner than moving to three.”
The WRU has previously revealed its five-year ambition to build the game, including Wales breaking into the top five team in the world by 2029.
It has also previously announced funding to the regions will rise this July – from the current £4.5m each – with incremental rises over the next three years to £6.5m each as well as wiping some of the regions’ debts.
But Welsh rugby is still waiting for that deal to be signed off.
“It has taken longer than I expected but even if we agreed the deal in October, the extra money wouldn’t come until July,” said Tierney.
“We’ve needed to take time to get this right. We could have imposed the agreement but the relationship [with the regions] is important. We need to trust each other.”
