I took a look at my GbG data for last season from FOE Helper and found similar to what Owl did (can't say for sure it's on par as
@Owl II you didn't mention how many rewards you got all total; or at least I didn't see it.)
Since folks don't believe screenshots - no point in posting them, but here are the data points I see that matter:
Total fights/negotiations: 7,156
Total rewards: 1,868
Total diamonds: 68 packs of 25 (1,700)
Actual Reward result: 40.8% - not quite the suggested 48/50% number.
Diamonds: 2.3% in total rewards
Now, if I did 10,000 fights instead of 7,156 and the percentages all held true that would be 2,376 diamonds for the season. Owl was just a bit lower at 2,200 diamonds for 10,530 fights.
I see in the discourse that the math error was eventually remedied, but it's funny how 2,500 per season would be considered too much when a player with decent diamond farms can pull that in every day? As one of the top 10 hitters in my guild I find myself there more frequently for times when SCs need diamonds to get them ready asap to help lower attrition for sectors to be included in the current flip session so I spend a good portion of those diamonds right there in GbG. During the timeframe I brought my diamonds down to 29.5K for the event and as of today (partly into a new GBG season) I am at 30.8K, so I'm not 2.5K richer than before and I haven't spent diamonds on anything but SCs. I suppose, however, that a net gain of 828 diamonds every 1.36 GbG seasons (609 diamonds/season) is "too much to sustain" as well? Guess I should delete my diamond farms across 26 worlds that bring in 420 diamonds a day (ie: 144,000 diamonds a year) as well? Nah - don't think I will....but as Inno knows I'm not motivated enough to collect from 26 cities everyday.