I feel like it's just rolling a dice to see which division you get placed in. I won all 5 of my matches in the TDM series (with a 2.5+ k/d) and got placed near the middle of silver. I went over to Moshpit and won 3 and was put near the top of gold.
My roomate played his placement matches for the TDM series this morning and got put in platinum by winning 4 with an even k/d. How is it deciding where to put you?