In this match Sri Lanka team has its own fault because their players did not play well due to which they not give a strong target in the match and will lose the match. The reason for this is that they have lost the match before and that is why they have lost this series. If they had work hard they could have won the series with some effort. Their players gave the first target weak and besides, their bowler had put less pressure due to which they had lost in 32 overs. Besides, Australia team is a better and more effortful team due to which they have also won this series. Sri Lanka team players were weak due to which they have failed to achieve a big target.
Yes there was Sri Lanka poor play in match especially their weak hitting that resulted in small score to chase was why they lost both game and overall series to Australia. Just like you I also think with more effort and improved play particularly in scoring more runs and their bowlers putting more pressure on opposing team Sri Lanka could have won. Ultimately we know Australia is more powerful team and they earned their series victory.