The question is definition of "gain". If stats-wise Hak makes considerable battle contribution by absolute and relative damage and spotting, and has good WR in the groupr, why plane losses matter? Kaga has a lot of plane losses, too, but she is still strong, because she can send many waves. It's just a feature of a ship - weaker planes, but more of them. Still gets the job done. On the contrary, Saipan has fewer planes, but they are stronger individually. Gets the job done as well.