Hint: and Stafford can't catch it.

Asking who is more valuable to the Rams, Stafford or Kupp, is like asking which is more valuable to human life: air or food? They are equally as valuable, each serving different functions.

Kupp set WR records of all kinds on their heads this year. I'm not sure I've ever seen anything quite like it.
But, it was Stafford who was the triggerman; and without Stafford's abilities, Kupp's recording setting wouldn't have happened.