placements

That's how it's supposed to work. It's called a rank RESET for a reason. It's near impossible to place at or above your previous rank. Gold 4 to silver 2 isn't even that bad. Challengers and Masters and even Diamonds can only place as high as Plat 1.

Hes mmr was for a gold 2 player before it aswell

Here is a very detailed thread about how placements work: http://boards.na.leagueoflegends.com/en/c/gameplay-balance/E9nkYATc-psa-regarding-ranked-placement-and-seedings-for-all-who-are-confused