Here's the thing. DC's gameplans revolve around his threat of taking people down. This isn't a well guarded secret. The main reason his striking is as effective as it is, is because when guys go into the clinch with him they're preoccupied by his takedowns and don't watch for his dirty boxing. We've seen what happens when DC fights someone not at all worried about his wrestling, and it didn't go well for him.
None of this is to say that there isn't any way that DC can take Brock down, but I have no reason to believe Brock would be afraid of his wrestling, or even that he has a wrestling advantage. DC's wrestling is a higher level than Brock's but the size and strength he'll be giving up will throw a lot of that out the window. Those takedowns he landed tonight on Lewis flat out aren't going to work on Brock.