Probably by countering and putting Brock on his back. Or, he could likely stand up.lol
Brock is a monster on top, in his prime, but there's no evidence he's controlling grapplers/wrestlers of DC's caliber. DC has great technique and is strong.
Jones has only been taken down once or twice in his entire career and controlled for less than 10 secs combined, I don't know why that translates to DC somehow not being able to do what Cain did to Brock.