In the modern game of league, it is a flip of the coin......
Many teams now rely on tries off kicks, something that you cannot cap, because teams themselves cannot rely on it.
The thing is many teams when attempting a bomb, very very rarey does someone go up and get the bomb clean, these days they rely on a back back, a lucky bounce etc etc.....Bombs are generally lotteries.
Furthermore, some days most tries are scored around the posts, therefore an easier kick for goals and some days they are scored in the corner making kicks harder..
Also some refs for some reason keep a close "10 metre" and some others keep a larger.
Some days there are more penalties, making teams on the attack more
Some days teams just cant hang onto the ball, some days they can.
Some days teams turn up defensively, some days they dont.
At the end of the day, it is nothing more than luck......The reason why is because of the wrestling techniques that the NRL allows, they do this so they can artificially make the games closer at the expense of making the games a spectacle. Capping totals about 5-6 years was significantly easier, because the NRL has allowed the wrestle, thereby making pointsbharder to score, meaning to score, teams are bombing which means more luck.
Over and unders these days are around anywhere between 35-42.......Rarely you get anything more than that.
About 6-7 years ago, you used to see totals around 49-50, even once i saw 54.5