tzscan.io Balance on web site differs from their API calls

Question

I have noticed that Balance seen at https://tzscan.io that KT address may not always match exactly with their API calls https://api6.tzscan.io/v3/delegator_rewards/ and https://api6.tzscan.io/v3/delegator_rewards_with_details/. Why it is so?

For example look here -> this guy has 5.260984 XTZ according to web site, but if you look what API says about his balance for current cycle here, you may obtain 5.255260 XTZ for current cycle which is 79.

Now use this address KT1QBSRSm22E2a8oPgHux65aNW86XCcaXZVU and API will return the same balance as web site has. So my question why it is so? And where in API return we may find what web site has for first address? I did not find it anywhere in API return. To be precise, I did not find anywhere in API call https://api6.tzscan.io/v3/delegator_rewards/KT18ctUAoHCbvrZCWWrsoC76DK6ehV3MRXuq the ballance = 5.260984 XTZ

Answer 1

This is how delegator rewards work - when you are looking at the delegator rewards for a given cycle (e.g. cycle 79), the balance displayed is that from the snapshot, which occurred 7 cycles prior. This is because that is the balance used when calculating the bakers stake which produced the rewards (so it makes it easier for bakers to calculate % rewards of stake).

This is obiouvlsy different to the balance right now. Here is the balance from about 7 cycles ago (as you can see it matches the delegator rewards balance).