Question for a Riot employee

Hello! I just had a question of why BilgeRat Rumble isn't available. I understand the whole legacy skin thing, but before it was unavailable it was only like what, 270LP or something? Not to mention BilgeWater Swain, Bilgewater Katarina are still available. I didn't start playing Rumble til recently and I'm dying for a skin other than switching from Super Galaxy to Jungle over and over again.. and buying 5 Mystery skins a day every day they are available trying to get it is getting very expensive.. Any time frame of that skin becoming available when you guys open the 'legacy chest'? Thanks!~