It's a very asked question : are player's ranks important in ranked 5v5's ?

The answer is quite simple, no. As a player, it doesn't matter if you're gold 3 or master, you need communication and synergy. It is always better to know your teammates, to know their play styles and to be confident and comfortable with them. So to those who are low in ranks, I tell you no worries, all you need is good teammates :D