Ranks: Wood 1 (500 MMR), Wood 2 (550 MMR), Stone 1 (650 MMR), Stone 2 (750 MMR), Steel 1 (900 MMR), Steel 2 (950 MMR), Titanium (1000 MMR)

Images:

https://ae01.alicdn.com/kf/HTB1s_0WRFXXXXX5XVXXq6xXFXXXJ/2-color-Game-overwatch-LOGO-brooch-bronze-silver-charms-accessories-lapel-pin-badge-3-5-3.jpg

Titanium would be white, with a slight gleam "Texture" added onto the ImageLabel
Steel would be pure black, Stone would be a dark gray, and Wood would be brown.

If you're still confused, take a look at this: https://static1.squarespace.com/static/59af2189c534a58c97bd63b3/t/5a8d8ef8085229b836e618ca/1519226621473/Overwatch+rank+by+tier.jpg


Placements:
Users would play 10 games after a new season starts and would have an average MMR of 650 with no games played.
Each win is +25 MMR, each kill is +3 MMR
Each down is +2 MMR (does not count if you kill them)
Each loss is -12 MMR.

Let's say you win 8 placement matches, and lose 2, and you get 10 kills on each win, and for the 2 losses, 5 kills

8 * 25 = 200
3 * 80 =  240
-12 * 2 = -24
-24+20 = 4
650+464 = 1114
However, the maximum rank you can reach on placement matches are Steel 1, so this person would be set to 900, and then could be able to rank up.

Divisions:

Wood 1 (500 MMR) (520 Div 2), (530 Div 3), (540 Div 4) | Wood 2 (550 MMR), (570 Div 2) (600 Div 3) (630 Div 4) | Stone 1 (650 MMR), (670 Div 2), (700 Div 3), (730 Div 4) | Stone 2 (750 MMR), (800 Div 2), (830 Div 3), (870 Div 4) | Steel 1 (900 MMR), (910 Div 2), (920 Div 3), (935 Div 4) | Steel 2 (950 MMR), (960 Div 2), (970 Div 3), 985 (Div 4) | (, Titanium (1000 MMR)

There a season rewards for each stage, this could be a skin, a glider, some type of axe, etc.

The stages are: Wood, Stone, Steel, Titanium

Queue System:

In order to prevent long queue times for people to queue against people with their ranks, you could either:

a) Since winning is fairly a challenge, you can simply make it so you join any game, instead of going up against players your same level, it still should be decently hard to rank up

b) You can add a Free Play mode for people to play while waiting for a match. This does not affect your stats nor your MMR.

Leaderboards:
The top 100 players with the highest MMR would be on a global leaderboard. In-game, it will display players MMR, and rank with the leaderboard instance.

Final example:

You lose 7 placement matches, however, you win 3, on each of the 3 wins you get 8 kills

3*25 = 75
3*3*8 = 72
-12*7 = 84
75+72 = 147
147-84 = 63

750+63 = 813

You would be placed in Stone 2 Div 2.