Italian teams are not weak. However, they are not interested in spending a lot of money on squad formation. So even though the performance of Italian teams is stable, none of the Italian teams have a squad strong enough to win the Champions League title.
~Snip
However, this is enough to prove that teams from Serie A are no less competitive than teams in other leagues in Europe.
Apart from that, if you look further into history from 2000-2010, it is actually very rare for teams from Serie A to win trophies in the Champions League. Only AC Milan has been able to win the Champions League in several editions. So it could be that the reason why Serie A teams do not perform optimally when competing in international competitions may be because club management is reluctant to spend a lot of money. However, the management at Serie A clubs only form teams with not too much capital, but are still able to compete quite well. But even so, I am quite impressed with the teams in Serie A, because even though they don't spend a lot of money, their team can still be a team that is still respected in Europe. And for next season, my prediction is that the teams in Serie A will remain quite tough competitors in the Champions League. But to become champion, it might be a little impossible. Considering that big clubs like Real Madrid and Manchester City are getting stronger now.