What if the Federation deployed drones despite the "failed" DDG? I figure the Federation observed drone combat between Klingons and Kzintis, considered them potentially worthwhile despite existing Y155 problems, and came up with an alternative quick-deployment capability in order to test combat concepts.

For example: Fed CA/DD able to launch a drone from its probe launcher. It takes a turn to load drone into launcher, cannot launch probe during drone loading or firing, can only use Type I drone from the relevant period, and only carries a number of drones equivalent to its probe payload (has both). No scatter pack, ADD, or specialized drones, just Fed units able to fire drones before they had racks for them.