Basically Serie A was a competitive league in the past at least in the 90s and in fact, its popularity is better than the EPL at that time where the top players were in Serie A. Like Zidane who even before to Madrid Zidane started at Juventus and then there are other top names such as Crespo, Shevchenko, Baggio, Maldini, Cannavaro, Pirlo, Seedorf and many others.
Serie A in 1990s and 2000s is the most competitive and attractive league in Europe. Back in those decades, you can find best players from defensive, midfield to attacking systems in Serie A. They fight each other and support, motivate each other to be better. Best strikers help best defenders to improve their defense skills and oppositely best defenders help best strikers to be better too.
But after Serie A got a case regarding the match-fixing scandal, after that Serie A's prestige decreased and now yes, I admit that Serie A teams have bounced back and of course that makes the league more competitive. Regarding the Champions League, it cannot be used as a benchmark because even the EPL, which is one of the most competitive leagues in this era, can still be beaten in the Champions League. In fact, yesterday's top three EPL can be beaten with just one team and that is Real Madrid.
The collapse of Serie A started with Lazio, Parma, Fiorentina after their presidents over paid for transfer and salary. Then debt, loan call, bankruptcy come and best players leave Serie A to other leagues. Calciopoli makes it worse.
I think Serie A is in a slow recovery and their system for youth players is not good as Bundesliga. It will constrains their recovery in next few years. If you are not rich financially, you must have good home-grown players. Serie A clubs are lack both of these things.