And last Sunday, after Collinsworth’s vocal disbelief about the unflagged McClain hit on Miller, the N.F.L.’s director of officiating, Carl Johnson, called the NBC truck to confirm that the hit was, in fact, illegal  basically saying that Collinsworth was right and that the league knew it. McClain was later fined $40,000, a delayed penalty considerably less instructive to fans and young players than Collinsworth’s live, confident commentary.

Fred Gaudelli, the producer of “Sunday Night Football,” said that Collinsworth’s outlook had influenced NBC’s use of in-game video.

“We showed the Miller hit, but we weren’t celebrating, ‘Wow, what a great hit by Jameel McClain!’ ”Gaudelli said. “We are all sensitized to what is going on now. Five years ago, we’d be saying: ‘What a hit! Wow! Let’s play this from five angles!’ Five years ago you would have had a much different way to characterize it and cover it.”

Collinsworth’s language and tone can be less overt, evident only when juxtaposed with that of other announcers, including his broadcast partner, Al Michaels. In last Sunday’s Pittsburgh-Baltimore game, after Steelers quarterback Ben Roethlisberger had his nose broken, Michaels provided some drama  “There’s Roethlisberger, with the bloody nose, and the bloody uniform”  while Collinsworth expressed more horror.

“That nose is crooked; oh, my gosh, look at his nose,” Collinsworth said over one close-up. He repeatedly pointed out that Roethlisberger had been hit by a wayward punch from Ravens defensive tackle Haloti Ngata, which is supposed to be illegal but drew no flag. (Ngata was subsequently fined $15,000 by the league.)

After McClain later crashed through Miller’s head on the catch attempt, Michaels explained that Miller had exacerbated the collision by ducking slightly before impact and said, “You’re going to have situations like that, no matter what the rules are.”

Michaels’s reputation for professionalism and care suggests that these more subliminal differences principally derive from the momentum of his decades of N.F.L. play-by-play. (And, Michaels said in a telephone interview, Collinsworth’s having played the game.) Michaels said that he mostly tries to convey the recent rules confusion among players and coaches, and that he tries to avoid expressing the opinion that Collinsworth is there to provide.