In my opinion a ranking system should work as such or near it. I feel there is a way to introduce the rating system plus the 1-50 system.
You start at 1. Once you reach level 25 you enter the “true skill ranking”. Your skill will be at 1200 or such. Every 50 points you gain a level, to achieve a 50 you would need 2500 or more possibly. Factors will be Friendly Fire, Betraying, Assists, Deaths, Kills, Objectives, Accuracy, Movement, Winning, and losing.
Friendly Fire - Reduction of points by an approximation of (x) or more points per bullet hitting a teammate.
Betraying - Betraying two or more times on a single teammate, or 4 or more teammates; will inflict a Derank and put in the lower priority ladder of matchmaking.
Assists - By assisting you will achieve a bonus of (x) points per bullet landing on a terminated enemy, a mulitplier is introduced when the assisted teammate achieves a multikill.
Deaths - By death you will be deducted approximately (x) points or more. A multiplier is introduced if you survive after a certain amount of time after initiation of the firefight which grants you points (reducing the amount deducted; can not exceed the base amount that is deducted) for surviving after a period of time.
Kills - By killing an enemy teammate you are awarded (x) points plus the amount of shots landed on an enemy. an additional (x) points is awarded for every multikill.
Objectives - By completing an objective; bomb planting, flag capture, flag return, etc. You are rewarded (x) points
Accuracy - (In halo 2 there was a statistic that introduced your Accuracy rating which I dearly miss; no pun intended). By achieving a higher accuracy in a match than your average accuracy you are rewarded (x) points for every percent more than your average.
Movement - Typically matches are won by progression and map control, by obtaining control of the map you are ensured victory quite often, but for those who are on the prowl can be rewarded greatly more so.
Winning - You’ve became victorious and are rewarded greatly for your services. (x) points are rewarded.
Losing - You’ve lost a battle, you are deducted (x) points, this is static amount an a multiplier is introduced outside a 2 level range to encourage same skill level gameplay to prevent “boosting”.
Party - If you are in party larger that is intended for a single team then the party is awarded no points to prevent boosting, but deduction will still occur.
Feel free to comment or suggest what should change 
I really liked the 1-50 system and I miss it greatly, it was what Halo was about in the day.
