Good tennis from Cilic last week.9 titles already is impressive,however they're all 250 and the opponents he had to beat...I'd rate Ljubo's 9 titles much higher than Cilic's.
I don't think that you're making a fair comparison. At age 24, which is Marin's age now, Ivan had only one title. He won his sole MS title at age 30. Marin still has 6 years, providing he's healthy, to catch up.