This is the A-League's biggest problem, the Italian international midfielder said.
Diamanti, 37, last year joined the Melbourne-based club as it prepared for its debut season in the competition.
Diamanti was magnanimous in his praise for the overall quality of the league but could not stress strongly enough the importance of having promotion and relegation to go with a second division.
“Australian club football has many strengths from what I’ve seen,” Diamanti said.
“The football here is organised and disciplined, which is very important. It is physical and pretty fast. The general attitude is wonderful and I have seen a few interesting young players who have the potential to grow.
“I have noticed however that many players are happy to just stick to their job but are unable to adapt to changing match situations. In Italy, you learn from an early age to be tactically flexible so you can deal with different circumstances.
“I believe, however, that the league’s greatest weakness is the glaring absence of a second division.
“The threat of relegation will have all the clubs on edge for the whole season.
“At an individual level, nothing improves a player more than a dose of healthy pressure that comes from the fear of being in a team that gets relegated and has to face the fans and media. I know what it’s like.
“On the other hand, the prospect of promotion will encourage clubs to invest more to earn a spot in the A-League which should be based on merit. This is how football works.”
Diamanti has been one of the stand-out performers in the competition and his eye-catching skills have helped Western United reach the finals.
Diamanti, who has played with and against some of the world’s best players in a professional career spanning almost two decades, adapted instantly to Australian football even though at times it appears some of the less experienced players are not on his same wavelength.
“Only a few people can read my mind,” he quipped.
“Seriously, I have had that problem for many years, except when I played for Italy alongside some great champions.
”Remember, this is our first season and the more we train together the understanding grows in terms of what I can do for the team and what my teammates expect when I have the ball.
“Actually, this being our first year, we are doing great things for the people in our area and we are proud to have made the finals with two matches to spare.”
Diamanti is a happy-go-lucky footballer who has been around for so long he can afford to take the game in his sumptuous stride because he does not feel the pressure to perform any more.
He gives the impression that he loves nothing more than having a ball with his teammates, spraying passes all over the field, providing assists and coming up with quality goals like the two cheeky chips that helped beat Western Sydney Wanderers 5-3 last week.
Yet there is a mean side to the man who likes to call himself ‘Alino’.
“Yes, I just love the game because it has given me everything and that is why I play with a smile on my face,” he said.
“But don’t be misled. I am also very demanding on my teammates, the technical staff and the club. I do this because I know that to be successful you need to aim high and if there is something I don’t like I will not hesitate to make my point. Not only because I am the captain but also because that is the way I am.”
So how far can Western United go in their debut season? Can he add the A-League championship to the Chinese Super League title he won with Guangzhou Evergrande in 2014?
“All teams left in the competition are strong but we are very proud of our achievements and we will continue to work hard, believe in ourselves and keep surprising the doubters,” he said.
“We are playing well but we have to strike while the iron is hot, which is what I’ve told the boys.
“We go into the finals as outsiders and want to be as ‘annoying’ a team as can be.
“You know why? Because the teams that win trophies are usually the ones that are a pain in the bum and the teams that are 'nice' never win.”
