there often complains about lags while watching a game live via watch game tab. During a game I watched today and saw the log mentioning out of order packs and data drops because of that.
Now I'm not sure how Valve is handling the Data for live games, but it seems there is no buffer that can hold 1-5 packets to be able to place late incoming packs in the right order. The only reason why that would be is to make sure the spectator chat is in sync, but I can fathom why chat should be prioritized over a smooth watching experience.

My suggestion is a dynamical "replay constructor" for live games with a variable package buffer. Since the game already logs out of order packages and how much a package is ahead, you could use it to calculate if the buffer needs to be increased to a "statistical out of order average"

Honestly with a 2min delay you could also have 5-10 sec buffer for all the clients and it would difference for the average viewer, cheater could may use this to reduce the delay to 1:50, but how big would that impact the gameplay anyways and is it more important to a overall enjoyable viewing in game experience.

I have no clue what's the exact purpose of Delta Packs but they might be used to sync all the other packed on, because the moment I got missing Delta Packs the game didn't know what to do and froze every on the map in one place. So I would appreciate it if someone have some info on that.