Ah gotcha. Yeah I took a break too because my buddy who I was doing all the skirmish achievements with had to go away for a while so I started playing RE5 and HAWX and Halo Wars.
Hey man, sorry I just noticed your message. Yeah I just beat the Russian campaign on Hardcore for the 3rd time to HOPEFULLY get OpFor. This time I played the Prelude to War first and then went about beating it. In Hardcore, your opponents will ALWAYS be at least 3-4 ranks ahead of you. The only thing I can really say is to know the combat triangle and what kills what (especially when infantry and engineers get into cover) and then protecting your units (evacuate) as they rank up and maybe even resorting to using a WMD to kill someone stealing an Uplink to keep the Victory countdown timer going.
I never do raid missions and I typically try to do battles and usually go with the following deployment order: 2 transports, 2 tanks, 2 artillery, 3 gunships. This gives me cover for everything the opponent throws at me.