It’s not like we’ve seen the sum totality of their work. They might have great specs scripts out there, or done some great drafts on those turds that were then then rewritten by someone else or noted to death by the studio.
Or they might just have gotten the job because they’re good in meetings and loyal stenographers for the producers’ dumb ideas. Who can say?
Unless it’s Aaron Sorkin or someone, attributing credit/blame to writers is generally a pretty dicey proposition, especially for big studio movies.