I wonder where you got your information from, AT&T?
This is a study I saw that gives AT&T an edge performance on initial download speed, however if you read the entire report, it shows that the reliability of using LTE for all data in different markets shows Verizon continues to be the better carrier.
FWIW- My ipad3 reports exactly what the study stated, 15 down and 8 up. using OOKLA Interesting coincidence.
No, it wasn't from AT&T. I'll dig it up, I saw it a few weeks back. In the meantime, this is my LTE performance on AT&T.