I think it's better if we stick to the facts. Marotta grappled Vidal out of Bayern Münich's hands, so he clearly has the ability to compete with clubs. And it should be noted that Bayern Münich is a really big club. What Marotta cannot do, however, is compete against clubs that have a lot more funds than Juventus, clubs such as Manchester City. This is what happened to the Dzeko- and Aguero-transfers. There's a big difference between that and chickening out.
As for Rossi, he pulled out because Villareal rated him a lot higher than Juve. If you ask me, that's a fair reason for pulling out of any deal. Villareal probably never wanted to sell him anyway, there are many indicators of this.