Dude,seriously..??The guy was free,plus he has played for the National for both World Cup and Euro,have played Champions League football,and not to mention that there were several clubs interested for his signing,he didnt sign a new contract with Ajax,because he wanted to go to a bigger club and what bigger club than Juve ayy,come on just to add depth,You may say his injured and all that but you'll see what i mean when he revives..
And as for Ivanovic,a great club needs to take chances especially with our current condition,we will have to take chances and risks are always there..If we were to risk on any player for that defense spot,then Ivanovic is my man..