The following items are calculating differently in Lootrank than they are at WoWhead.
Lootrank Template: http://www.guildox.com/go/wr.asp?s7=2&Art=1&s1=2&s3=2&Max=21&s6=1&Gem=3&...
WoWhead Template: http://www.wowhead.com/items?filter=sl=5;ub=6;cr=166:79:180;crs=5:3:3;crv=0:0:0;gm=3;rf=1;wt=170:20:45:46:119:117:22:41:103:32;wtv=1.3:1.2:1:1:0.95:0.9:0.85:0.4:0.1:0.1;eb=1
Breastplate of Ancient Steel: 5718.45 on Lootrank, 6706 on WoWhead
Ghost Reaver's Breastplate: 5459.25 on Lootrank, 6397 on WoWhead. WoWhead also has it using different gems.
Ghost Reaver's Gauntlets: 3530.35 on Lootrank, 4380 on WoWhead.
Masterwork Spiritblade Decimator: 2569.99 on Lootrank, 3419 on WoWhead.
There may be more but this is what jumped out at me. Oddly enough they're all crafted items so if there's an easy way to do it I'd suggest refreshing all crafted items.