Allakhazam's Item Upgrader - Item ScoreFollow

Can anyone explain to me how the item scores are determined?

Under the Items dropdown, upgrades tab, each item is assigned not only an item level, but an item score. In my case, I have the Valorous Frostfire Robe (disregard if my profile says Heroes, thats old data). The robe has an item score of 483. I also have the Digested Silken Robes, with a score of 522. Both are item level 213. How is the score determined? Are the Digested Silken Robes really the highest/best cloth chest item?

Sorry, WoW.