Regarding WWE Universal Champion Brock Lesnar not being on Monday's RAW in Anaheim, Justin Barrasso of Sports Illustrated reports that Lesnar was scheduled for the show but he has already went past the number of contractual dates on his current WWE contract and as he's aware that he will be losing the title to Roman Reigns at WrestleMania 34, Lesnar is said to be far more interested in negotiating his next WWE contract than being a "team player" on the current deal.
As noted, the face off between Lesnar and Reigns was in multiple scripts that were done for Monday's RAW, and WWE was still advertising Lesnar after RAW hit the air. The segment was scheduled to take place in the second hour and at one point would have Lesnar calling Reigns a "b---h," according to PWInsider. It was reported by Dave Meltzer of F4Wonline.com that Lesnar being nixed from the show may have been a creative change made at the last minute. WWE's goal for the Reigns vs. Lesnar build is to get Reigns cheered by fans, which is something that isn't always guaranteed, leading to a positive reaction when he wins the title at WrestleMania 34. Officials also want the build to Reigns vs. Lesnar to come across like a shoot as much as possible, which is where Reigns' worked-shoot promo from RAW comes in.
It was also noted by Barrasso that we still could see a Ronda Rousey - Heyman partnership on TV but Heyman working as Ronda's on-screen advocate depends on her ability to resonate with the fans.