I am a fairly new player in FAF, but have played the game for like 13 years. I would agree the biggest thing I to overcome was relearning to play the game. The experience I had to go on was that of the Supcom campaign, which didn’t really help in my team games. The biggest way I improved was watching casts of Supcom and watching games after I got killed in the first 5 mins.
I would think the best approach to this would to offer a bootcamp thing would kind of work like survival games. You could set it up to matchmake one noob and a pro to go through a like 20 min match where how the AI tries to kills the com rotates. One match the enemy com makes mercies, or just t1 gunships.
The mission ending once the enemy strategy has been defeated
I also think you could make ladder in the threat being T1-T4 and let the player choose which they would like to deal with.
You could have it just be two slots of any ranking, but the idea is the matches are quick, there is a team element and noobs can learn how to defend the basic early attacks.
You could even have little missions like build the hydro, make a smd, or build flak so there is some guide.