How come 1200 bots play so different as compared to 1200 players?
The bot ratings are generally acknowledged to be overstated. Bot play strength is limited by the mandated strategies they are programmed to follow. Announcing that you like to sacrifice before a game makes it easier for their human opponents to adjust. The bots cannot adjust.
The ratings would be more accurate if the bots were allowed to play rated games. However, this comes with its own set of problems.
Bots tend to be generally overrated than what their rating states them to be. Bots on the lower end of the spectrum especially (250 -1200) just give away pieces whenever they feel like it, not cause of pressure or time or whatever reason unlike real players. I guess you could use them as warm-up before going online and seeing if your in good shape to play but they certainly do not play or think like real players.