Twisted treeline ranking system?

My two friends and I recently played the placements for twisted treeline 3v3s. We won the first match, then lost a very close second. won our third, lost the fourth, then won the fifth. so with 3-2 we assumed our ranking wouldn't be good but hopefully not, yeah you guessed it, bronze 5. Can someone explain how we could get placed in bronze 5 with 3 wins and 2 losses. Please let me know, thanks.