TPAs are wildly overstated, at least based on the most recently published information. As an aside, I think it's pretty funny that in 2018 the NRL proudly boasted that it was improving the "transparency and integrity of the code's contract process" by making public TPA amounts... but good luck finding that data for more recent seasons. Just quietly dropped, it seems. Anyway, FWIW:
https://www.nrl.com/news/2018/12/13...ents-public-and-strengthens-contract-process/
According to the NRL, TPAs actually fell since then - to 3% of the total cap last year from 5.5% in 2018:
https://www.nrl.com/news/2022/04/29/nrl-unpacked-how-does-the-salary-cap-work/
Basically, if you're looking for a game changer in how the cap works it almost certainly won't come in the registered TPA space. The Roosters had about $200k total of TPAs in 2018, which might be a difference maker in, what, two front line free agent contracts? It would hardly explain why a raft of top line talent is signed for them on obvious unders.
What I'm saying is: you might as well just say illegal "payments" - if it's happening (which I think is entirely possible), it probably isn't in the form of TPAs.