I would be very curious to see how you're managing 5k rep a day and only doing .17% damage in cerb/baal. Even with 100% rep bonus from cities your math doesn't add up. Not to mention you're on an old server as a new player. You're not going to be significant rep from cerb, baal, or rag. At most I could see you managing 2500 a day.
Firstly 2000 rep from attacking others in arena
Secondly 679 (709) reps i gain per day as rewards in arena
Thirdly 102 reps for investment
Fourthly about 20 reps in baal ( I dont get chance to do cerb )
Fifthly rag gives me about 100 rep
Sixthly lottery chests in casino I get 100 rep sometimes 200 reps the majority of the time (Not mentioning the lvl 1 chips)
Already this adds up to 3810 reps
I push myself to get as much reps as possible ... I should be 120k reps on sunday
i am getting roughly 20k a day, thats 40-50% damage at banishes, 3-4k from ragna along with other rewards. however, i am in the top 2 on our server. i don't think the question here should not be how much is possible, the question should be to find out what the "average joe" player gets and with all rewards, i dont think its more than 3k a day (played daily, doing all events and having no life) and that woud give you a playtime of roughly 3 years (assuming you will have a few days you get up to 5k) to get marshal.
i would like to emphasize at this point that the promotions got a reform (due to royal challenge, pro accounts, etc) but the way on how to gain reputation itself has not changed. IMHO any playtime exceeding 1 year and not getting to the max promotion/title is proof for a desperately need on how to increase the average reputation gained.