fathom - 6:51 am on Apr 16, 2012 (gmt 0)

I don't see anything that would lead me to this conclusion Sgt Kickaxe.

Agreed

My best hypothesis here would be that they handle anchor text differently

If you have a diverse link anchor text profile... you don't see any depreciation in the anchors' value.

If your profile is predominantly a few different phrases... that's a red flag for unnatural.