Actually a great shout this. I'll admit I have on occasions sold my STs for above face value on StubHub when I couldn't make it and the demand was there (Liverpool and Man U only really), but this has always been more than offset by the amount of times I've sold them for 5 or 10 pound for the likes of Palace and Fulham on a Wednesday night! It's supply and demand.
The thing is, for games like the derby, if a ST holder can't make it, people will now probably just sell their tickets directly to someone for more than they would get through this new re-sale site, so people shouldn't expect to see a load of face-value 'big game' tickets for sale on there. And also, for the games which were usually available for much below face-value on StubHub, these will now be full face-value on the new re-sale site, so ultimately non-regular match goers will likely be paying more for their tickets overall.