Invasion Slayer on Hemmorhage

Why do the Spartans get such a huge advantage on this map/gametype combo? I can’t recall one time where playing as the Elites my team was able to win whereas when I am the Spartans I can’t recall a time I have lost. It has been like this since I first played the game and I thought that after being out for over a year and a half stuff like this would be fixed. But the only updates we get are the anniversary crap.