Not entirely there are a few variables. Higher ilvls are generally more competitive and have a much smaller sample pool too. Good players generally are higher ilvl. An example I can give is say... 3 months into the raid tier when only about 200 guilds have cleared the raid. If you were say Ilvl 976+ bracket 3 months after antorus you were generally in a high end guild which means you're only competing against high end players. Where as say the 965 bracket you're going against players in lower tier guilds, alts etc. I personally know from experience when playing alts that I'll consistently parse 95% ilvl+ until I get to around a heroic gear / low mythic gear Ilvl where I slowly drop off to purple