Speaking from the other side, I just recently started playing and just hit Epic+ as a result of the previous RC, these RC boost my progression so fast I might still be in SR if they weren't around.
My current lineup is all UR pros and an untrained RC Rodman. Of those UR pros, one is the UR MJ pro from ladder rewards and the other is a Varejao pair I got from the Cavs/Warrior RC which I started playing halfway through. What that means is even though I'm already in Epic tier, I've only legtimiately gotten 2 cards through the draft board. Since hitting epic I've gotten a few more UR dupes, but when I just hit SR, getting two UR Varajao's let me catapult into UR and get another UR freebie while I waited for the UR MJ so that I could progress through UR ranks.
However, I stalled in UR+ with an MJ pro, Varejao pro, and a single SR pro, and I would have needed another two UR pros to hit epic. That's when I got the Rodman RC and got into Epic with it even when I was struggling to get another SR pro.
Now that I'm in Epic, getting Kobe RC will go a long way towards getting into legendary, and I think that if I leave Kobe and Rodman untrained, I need two epic pros to get there, and only one if I train them both. At that point, my LU will likely be: Legendary freebie, Epic pro, UR pro, RC Rodman, RC Kobe. My LU will be 80% cards I didn't legitimately draft since I'll probably use the UR MJ since it's the best stats.
The beauty of RC is that there's no correlation of rank and points. A person who just started playing two days ago and runs a 3-2 of rare pros has the capability of getting an RC pro, probably just as easily as anyone else.
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