bɪkˈʌz ðə nˈæʃənəl fˈʊtbɔːl lˈiːɡ hˈædənt kˈɛpt əfˈɪʃəl stɐtˈɪstɪks ɪn ɪts fˈɜːst θˈɜːtiːn sˈiːzənz, nˈɑːlɪdʒ ʌvðə pˈiəɹɪəd wʌz ɛkstɹˈiːmli lˈɪmɪɾᵻd.
Because the National Football League hadn't kept official statistics in its first thirteen seasons, knowledge of the period was extremely limited.