I wish we could have seen Mack at 100% at A-Day. That little injury affected him, and he had to leave the game early. CKD has said Mack is light years better than last year. And has been consistent in making plays. If the OL is underperforming, then Russell may the guy for his scrambling ability. But don't count Mack out just yet.
I think the balanced view is that the competition will go into the fall. The fans won't pick the QB, but now the fans have seen with their own eyes how special Russell is. It was bad luck for Mack to get injured when he did, no doubt.
It may be the case that we have two very high level QBs, which is what the staff has been saying all along. Mack had a couple of brilliant throws, despite the slower day.
But as good 'ole Lou Holtz (RIP) once said, "If you have two quarterbacks, you don't have one."
Unless the momentum drastically changes, I think Mack just may be the unlucky one of having KR as his main competition. The young stud is just so talented, I don't know how they keep him off the field.
I imagine it'll be a competition through "fall camp" (which is roughly about the 1st two weeks of practice, IIRC) but when it ends, CKD will have to make a decision when it comes to install time and whichever one it is will need all the snaps they can get. It may be something we don't even know in terms of an announcement, but one of them needs the majority of snaps.
Knowing what we know now, I'll be surprised if KR doesn't emerge as the starter, but, whoever starts, I imagine both of them will play the first game or two.