The placements depend upon various factors. The most important thing is the brand name of the institute, facilities in the institute, and the quality of students admitted.
Taking a new IIIT into picture, there are various possibilities that the placements are low:
With the listed points, it would be difficult to expect great placement from new companies in the new IIITs (Vadodara, Kota, Guwahati, etc.). But these problems are for temporary years. The institutes develop over the time and show great placements like that of top IIITs.