Originally, Rampage was set to come out two weeks before Avengers: Infinity War, and with no major studio tentpoles set for release on that weekend in-between, Rampage was likely to have a solid opening weekend and potentially a strong second weekend as well, before the Avengers showed up and ate its lunch.
By jumping back a weekend, Rampage puts that second open weekend back between itself and Infinity War.
The Hollywood Reporter says that Rampage has been doing well with test audiences, so the studio may be thinking that second weekend could be key to the film’s success.
Anybody who isn’t so sure that a movie based on a 1980s quarter muncher can actually be that good might be convinced by word of mouth coming out of the first weekend.