Players ability could be classified as 3 types in cba:

Leader This type of players tends to give advice to ally. As a leader type player you have to know the game in details, and know what is going to happen with those civ and players. Plus communication skills.

Boomer This type of players can boom very fast. They raze fast, farm kill and build up his army and extend his base to outside, need to be very good in multi task as they have to build and fight at the same time.

Fighter This type of players can gain number of kills in the most efficient way. They feed less and get the most kill, knowing different formats and stands used in different situations.

It is possible to have more then 1 type of ability, especially for the pro players.
It is also possible to have neither 1 of the above ability, then you are known as a type of players that commonly appear at lobby titles : NOOB

You need to have very good knowledge on cba in order to give the best advice. Will inca beat byz? Will camel archer received the team bonus from Saracens / Indian ? Do you remember the tech tree for all civs? All these are basic.
You have to know how the game will go. Need wall or not, what unit to make.
In the first second when you see the civ you need to draf the plan. Who going to raze first, or going to rush, all these need coordination and work as a team.
You have to know the players. You need to know what your ally can do with his civ. And know your enemy too.
Skills required: reading the mini map, to know what's going on. Communication skill, simple and effective would be the best.

Civ good for leader would be some civ that requires less attention, so he can pay attention on the whole map. Like Portugal, Persia, etc.

To boom you need to raze fast and build fast, then advance to castle age and imp fast.
To raze fast, you need good skill in stacking or sneak in a gate if you are melee unit.
After you get villagers, you have to build up your base, mass up army to max 250 population , and fight at the same time. You need to care about snipping vil and expanding at the same time.
To be a good boomer you have to multi task, so you must use all kind of hotkey, and the best is you design your own hotkey.
It would be good if you are good in fight too, but the key for boom is mass up 250 army and control the map.

Civ good for boomer will be the boom civ, such as Magyar, Malay, Ethiopia, Viking. And civ that can fast imp like Azt Celt, or civ that 1 raze could get vil.

The ability to kill unit and feeding less. Patrolling is the most basic part. If players using range unit, they could do hit and run. Normally if the unit can stay out of range the enemy, you should have a very decent kill to death ratio. When range unit against range unit, you can do runner, or hit and run if you have longer range. When using melee unit, you able to use different formats and stands to catch archer or against othes melee unit, and they can do runner or tanking his ally which is range unit. They can del low health unit fast to avoid feeding. With strong micro and fast reaction this type of players are strong in 1v1.

Civ suitable for this type would be the civ that move fast which can show their fast reaction, like Saracens, Mongol, Maya etc.

I define a noob would be bad in all 3 aspects.
In leader, noob can't communicate, or unwilling to cooperate. Don't have basic knowledge on civ and unit. They dont know who should raze first, always act alone.
In boom, if they build, thieir army will be idle（they claim they guarding his base for building safely ）; if they fight, their vil will be idle; their army lost at a higher rate than production of army, couldn't get max population even after long time; couldn't expand the base, after his base is fulled they start tower up his own base.
In fight, as range unit they bad at hit and run; as melee unit they feed a lot and don't know how to tank others. Bad in patrolling, not making good use of different stands and formation. They always think they have bad civ so they lose the fight.

Know about walling, block side during rush, know how to build up the base, just mean you are not new in cba. Actually some old players are still noob by my definition. It is ok to be a noob as everyone start at somewhere, but you need to know your level and try to improve. It is bad to blame your ally is weak or enemy stack with pro players. If you make yourself a pro, others pro will be willing to stack with you.