Moggi didn't 'discover' Zidane until he joined Juventus for two years. Marotta has signed good prospects of Appelt(s) and Sorensen, and we still haven't seen how they'll turn out.
What Marotta did last season is disastrous but his key signings for this season is one of the reasons Juve is on the top right now, I wouldn't dare to call it decent, it's a very good work. He can opt for less priced RB on Beck but he didn't; he can buy Aguero if he's willing to splash more money but he didin't; he can bow to those bastards at Udinese's will to price up Inler but he didn't; he bought Vidal, Licht, Pirlo, and Vucinic instead which have proved to be immense.
We still haven't seen what become of Krasic yet but what he did in his first half of season was sort of phenomenal, far better than Amauri.
My point is it's still a little early to judge Marotta, even comparing him to Moggi but nevertheless he did a good job on the previous transfer window and I'll give him credit for that.