I don't want to beat a dead horse, but the Rupp vs Derrick convo has many dynamics. This one being about a XC race, I don't know why anyone (And I am a huge Galen Rupp) would argue that Derrick is currently the better of the two. If we were in a world where Galen had just run 13:01 for 5000m on the track last weekend and Derrick did exactly what he did today, I would pick Derrick in a XC race. Because a fast 5000 on the track is NOT a XC race. And I acknowledge how strong of a runner Rupp is, how much strength work he and the NOP do, but that does not compare to the experiences of racing over hill and dale. And anyone (Jenny Simpson included) can tell you how hard it is to race XC when you haven't done it in awhile. To the best of my knowledge, Galen Rupp last ran a XC race in 2011 and hasn't done anything consistently since college (2009). Consider that Derrick has run at least one (if not three) XC races since leaving Stanford. Factor in that Derrick is no slouch as a runner in general and I would give him the edge.
The interesting thought is that Galen does a lot of work on grass as is. Their use of soft surface is well known, so I guess that would play somewhat of a small factor in the least.