Monday on RAW, WWE booked Mark Henry and Rusev in the main event segment to promote their Night of Champions match. The company did this because they were trying to save their “money” segment between Brock Lesnar and John Cena for the halftime of the Monday Night Football game. The company specifically filled fifteen to twenty minutes with commercials, backstage segments and promo spots so they could stall in order to get to halftime.
The company generally draws their best ratings in hour two of RAW, particularly during football season while fans switch back and forth. The idea was presumably to put their strongest segments and matches in those high-profile spots to get the most out of viewership habits and to promote Night of Champions.