It actually did pretty well in the theaters that bothered to show it. What really depressed its box office run is that so many theaters never played it in the first place. The brand is damaged.
Actually, it had a decent roll out (ha!), at over 3K screens. But I think what hurt it, generally, was lack of connection to Bumblebee (as in, BB wasn’t marketed as a “Transformers“ film), meaning the last major film to many would have been The Last Knight. It also didn’t help that films like Spiderverse were doing so well and major pushes were done for Flash and Elemental, which tied up a LOT of the premium seatings and extra screens the film might have had.
When I was tracking the film’s performance (over in the Rise of the Beasts Thread), the film was actually “holding” fairly well, and ended up doing “better” (relative to costs and box office) than films like Flash, Elemental and Indiana Jones, which cost FAR more and, in most cases, failed to deliver.
All told, the WW Box office was only $30 million behind Bumblebee (which, itself, competed against Spiderverse and a healthier theatrical market). Heck, the film even outgrossed BB domestically by about $30million! Considering the weaker theatrical market and the nature of the competing films? It didn’t do THAT bad.