Tennis made a valiant comeback this year. It never went away, not for those with a passion for the sport, but it needed what the Tower of Power band calls a “soul vaccination.” Some thoughts on the U.S. Open, which delivered mightily:

•Do people judge a three-act play at intermission? Take Rafael Nadal’s advice and forget about arguing “best ever” with careers still in progress. As he put it so well, “Let’s see how we finish.” Simply put, Nadal has 16 Grand Slam titles to Roger Federer’s 19, the two of them split this year’s majors, and there’s no end in sight.

•Since he was a kid, Nadal has put every ounce of his energy into every single shot, in matches or in practice. His knees have been killing him for years. And yet he holds the Open trophy — and he’s the only man ever to win the French Open and U.S. Open in the same year three times.

•A tip of the cap to Nadal’s uncle Toni who has coached him from the beginning and will retire at year’s end. Toni taught the lad to never give up on his desire, and that only a fool blames rackets for failure, subsequently smashing them to smithereens. Nadal did it once, and never again.

•As we remember from Jimmy Connors and John McEnroe, there’s nothing like some old-fashioned hatred to enliven a tennis match. But there’s nothing like true friendship, either. When Sloane Stephens held Madison Keys in a long embrace after the women’s final, it was one of the best sports moments of the year.

•Ranking the greatest female players of all time, the top six are basically set: Serena Williams, Steffi Graf, Martina Navratilova, Margaret Court, Chris Evert and Billie Jean King. Venus Williams, astounding in her longevity and unmatched for her contributions to the African American community and equal-prize-money campaigns, is just a step behind.

•Great to see Stephens’ mom getting the kind of attention she has not sought. Sloane lost her dad at an early age, but she was raised magnificently.

•Looking ahead to the 2018 major season: Serena, Victoria Azarenka, Novak Djokovic and Andy Murray all back and (ideally) at full strength. It is a landscape of promise.

Bruce Jenkins is a San Francisco Chronicle columnist. Email: bjenkins@sfchronicle.com Twitter: @Bruce_Jenkins1