Ronaldo at Real has won only one title in his time there (almost 8 years now). Pirlo at Milan won 2 in 8 years despite both having a star studded team during their time there.
As for Zizou, Id say he had seasons when his team was expected to win but didnt, but you need to consider injuries and form too in these scenarios. In 1999 without ADP we couldn't win the league, but should have finished higher (we were only 2 pts off 3rd place tho). 2000 we all know what happened on last matchday and 2001 we again were 2nd with only 2 pts behind Roma despite a weak start. Could and should have won 3-4 titles here and if ADP never got injured he probably would. Still, Serie A was a super strong league with 4-5 teams competing each year and as i said, he cant be expected to win it every year. In Real it was a different story. Once they sold Makelele they screwed up their team, had no one to balance their formation which was ridiculous, also the reason why they never were a serious threat in CL after 2003. Still should have won Primera in 2004. Cant blame him for 2005 and 2006, Ronaldinho was best in the world and Etoo was scoring for fun. Barca was better than them simply