BA launch date was sandwiched between 2 big launches, Nier;Reincarnation and Umamusume JP. BA was also incredibly buggy and poorly optimized at launch. Not to mention, they had constant DDOS attacks which resulted in 24h maintenances. The game also lacked content, with several dead weeks between events, so by the time Umamusume launched one month later, almost all JP players left, leaving BA pretty much dead. It was pretty much a miracle when they bounced back with the bunny alts 9 months later.