Truth be told rankings don't mean a lot.
Especially when it comes to niche markets. If you specialize in for instance medical liability or intellectual law, those are fields in which the law firms can be small and entirely catered to this one particular subject. They won't show up in rankings, but are great at what they do.
Aside from this lawyers make good money, but not the kind of money that means anything to a club the size of Juventus. I don't think they're skimping on lawyers.