I normally do not like to refer to statistics, because most of the times, they can be quite inaccurate due to inconsistencies mainly because of small sample size. But as you can see from the link below, byzantines have had a relatively very small winrate in the previous patches (https://aoestats.io/civ/Byzantines/RM_TEAM), calculated since update 39515, which had come out in July 27th of 2020. This cannot be explained by some of the most popular arguements: that there is too little sample size and that the civ is generally hard to play compared to others. Therefore, the civ itself must be weaker, so a buff could be needed. Also note that 1% winrate difference in teamgames is actually a way bigger difference in terms of “civ strength” (assuming that an objective value exists), than 1% winrate diffeerence in 1v1s, since in teamgames there are more players in each match.
So why do byzantines perform badly in teamgames? There can be several reasons:
They focus on trash
Trash units clearly have less emphasis in teamgames than in 1v1s, since in teamgames you can generate infinite gold much more efficiently than in 1v1s, given that trading is an option. Therefore their trash unit bonus doesn’t come in handy in the majority of the games, and their camels are still pretty weak despite the discount, since they lack both blast furnace and bloodlines.
Useless team bonus for teammates (monks heal 50% faster)
Healing is much more important in 1v1s than in teamgames, since in 1v1s your non-trash gold units are basicly limited at the end of the game, so it can be useful to have some monks to heal them. However in teamgames there is no such case. And people don’t use monks much anyways.
Their only real powerspike in teamgames is to fast-imp into arbalests.
Cataphracts are still a very expensive option. Other archer civs usually outperform byzantines, since they have proper eco bonus with usually military bonuses geared towards archers too. You can’t go skirmishers, because opponet’s teammate can easily kill them with knights.
Their only viable far late-game unit, the cataphract has several weaknesses
While they can’t be countered in the traditional way with halberdiers (given that the byzantine player has established a trade route), they are very weak to archers. They need too much castles to maintain proper production, because the training time is too high. They are incredibly bad in castle age, so you cannot start massing them early.
So how could they get buffed in teamgames, with a negligible effect on their 1v1 performance? (whether they are fine in 1v1s is another problem, let’s assume they are)
-New team bonus, with the original team bonus moved to the civilization bonus category
-Cataphract stats being adjusted, buffed
-Buff their imperial age powerspike
-New military/economy bonus mainly focused on the early game
Obviously all of these shouldn’t be implemented at once, this is only the “potential balance changes pool” from which we can choose a few.
-training time reduced to 17 seconds from 20 (for both non-elite and elite version)
-non-elite cataphract attack increased from 9 to 10
-cost -5 food (from 70 to 65)
-Imperial Age up bonus increased to -40%
-Team bonus (+50% healing rate for monks) swapped with free town watch, and also get free town patrol as team bonus
-Get blast furnace but lose plate mail armor (to counterbalance their halberdiers in 1v1, and to make their cataphracts a stronger far late-game unit. Generic paladins and cavaliers will still require the same hits to take out a halberdier, and that remains true vice versa).
-More benefitial team bonus to the team, easier teamwork
-Slithly stronger fast-imp arbalest powerspike
-Their camels won’t be very bad
-Cataphract will be a better far late-game unit, and it will be easier to transition into them
-In 1v1 the only remarkable changes are the imperial age cost decrease and free town patrol, therefore they won’t change much