FedEx 727 diversion?

This morning about 6 minutes ago this flight from MEM to ROA apparently diverted to Nashville for some reason. By looking at the sudden drop in speed appears to be an engine loss?

flightaware.com/live/flight/FDX1451

Perma-link to flight:
http://flightaware.com/live/flight/FDX1451/history/20120313/0854Z/KMEM/KROA

Looking at the tracklog graph, they begin descending about a minute or two BEFORE any drop in speed. I would think that speed would bleed-off before altitude if there was an engine failure. I’m thinking maybe a pressurization problem as they level off at FL150 for about 12 minutes.