If this is true then for the first time in a long time I'm going to be scared for Nog. He doesn't match up well with either of these guys honestly, but he probably has a better chance with Lesnar than Carwin.
Against Lesnar I see Nog being slammed a lot and eating a bunch of masterbation punches. On the feet Lesnar is slightly faster than Nog too. Still, I think against Brock the situation allows for a miracle submission in typical Nog style.
Against Carwin I can only see bad things honestly. Nog's striking defense is wide and he keeps his head straight up almost all the time. His head movement is non-existant too. If Shane doesn't decapitate Nog with the first big right he throws then he'll likely be able to finish Minotauro on the ground. Carwin doesn't have the speed Brock does but his punching power is far greater. I think Nog could win via a leg lock but I just don't see how even he could survive being hit by Shane.
If Nog can beat Lesnar by sub in your scenario, then he can definitely beat Carwin. Lesnar is now a good grappler and light years ahead of Carwin. Yeah Carwin has big hands--that's it. Hell, I'd say the match would look similar to Nog/Couture but with Nogeuira submitting Carwin--I doubt Nog is going to get knocked out without staph even with Carwin. Even Fedor couldn't knock out Nog.