Is this a thesis statement? football players in the nfl are subject to an automatic fifteen-yard penalty if they engage in an excessive touchdown celebration.

Well it depends if on what type of paper ypu are writing. If you are writing an informative essay then you would have a thesis thats has this outline

Intorduction-
Background information on the topic-
Thesis (3 claims or facts)

if you were talking about how football players get flags or football players in General you would say football players in the Nfl get aFlag for illegal celebration, also unnecessary roughness, and unsportsmanlike conduct.

99, multiply all the sides