FYI, I've collected data(via over a hundred player response) on this as far as its drop rate on chase goes and the average time frame for getting 4 frags is 2 years. This was before the rotation thing, so now things could be even longer.

That said, the ninja pool have changed as well, so this may or may not affect the drop rate further. So unfortunately the data is no longer correct. But still, it's a decent frame of reference. It's not really something you can reasonably wait for.