Me personally, I pay very close attention to it because depending on the sample size, you can often make a pretty good determination as to whether a player may or may not perform within reason of their normalized numbers, or even over or under perform. This is because a lot of players' histories will reveal that they come no where near their good looking numbers, while others who don't appear so hot will routinely over perform. I also find a player's performance history especially valuable when they have a history of playing decent defense at a position at which they have no rating. I will often use such players at that position even though they have no rating there, but plays the position well. It's a great way to save money in the Draft Center.