Instead of limiting this on players. Why not limit it on mercs?
Any player can enter ranked, if they wish so. However, their 3 mercs squad would have to all fulfill individual requirements set for those mercs.
Lets say, I have a squad of proxy, kira, sparks and want to enter ranked. Instead of being level 7,10 or 15 or whatever is set, I would have to have fullfilled every requirement for these mercs.
These numbers are just an example.
Proxy - having planted 50 bombs, 100 mines, having 100 000 game mode xp, having 50 000 combat xp.
Kira - using laser 20 times, dropping down ammo station 30 times, having 100 000 support xp, having 50 000 combat xp, having 50 000 game mode xp
Sparks - throwing out 100 medpacks, reviving 100 players, having 300 000 support xp, having 50 000 combat xp.
These are individual, always could be tailored to each merc for a level that is acceptable to know the merc and use him properly.
Currently, there is a problem with new players, that me and my friends and probably most of you noticed and that is, that no ammo, no healing station, no medpacks on the ground, no revives, no nothing from newbies. And this is far more dangerous for ranked, than a simple skill. And the normal game itself. Raising a level requirement wont solve anything.
Game currently tracks a lot of these things and we already have a profile to show us some. Therefore setting these minimal requirements and expanding a profile, would allow more transparency, increase more awareness between players and would ensure, that players dont go into ranked without knowing mercs.
To expand on my example, lets say I would have just bought rhino and want him to play. I will put him in my squad. I will play a game or two, find myself playing awesome with him and want to go ranked. Because I am confident in my skills and rhino was easy for me to play. However, in just two games, I was not able to fullfil all requirements set for rhino. Therefore game wont let me queue with him in my squad. And I have to have more playtime to reach those requirements. Only then the game will let me go ranked with him.
This wont ensure you have a skill for ranked, but it will ensure you have enough experience and knowledge of the mercs in your squad to enter it and not act as a clueless noob. Simple level requirement is not enough, we need to have complex system that ensure that ranked is played by competent people who know what they are doing. That would ensure that skill decides the match and the team that wins is better.
PS: I wonder if this is even possible.