Analyzing John Isner's Place in American Tennis in the Post-Andy Roddick Era

John Isner is single-handedly keeping American men's tennis from dissipating into obscurity.

Isner upset No. 5 Kei Nishikori, 6-4, 6-3, in the quarterfinals of the Miami Open. It was his second win over a Top 10 player this week. He defeated No. 6 Milos Raonic Tuesday night. He will face No. 1 Novak Djokovic in the semifinals. 

Ranked No. 24, Isner is the first American man to reach the semifinals in Miami since Mardy Fish in 2011.

Isner is the only American male ranked in the Top 40. Andy Roddick was the last American man to win a Grand Slam, the 2003 U.S. Open. The last time an American reached the finals of a Grand Slam was in 2009, when Roddick lost a five-set thriller to Roger Federer at Wimbledon.

Robby Ginepri's 2005 appearance in the semifinals of the U.S. Open remains the best Slam performance since Roddick's among active American players. How active is debatable. Ginepri is ranked No. 255 and has yet to play a match on the ATP Tour this year.

Where does Isner stand among American men in the post-Roddick era?

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He's the best the U.S. has to offer. 

Isner has been ranked as high as No. 9. He's won nine titles, none of them majors or masters. He turns 30 later this month. He's had a solid career, yet he goes into every Grand Slam as a long-shot to win.

In the post-Roddick era, Isner has been the most consistent American player. However, when compared to American players from the pre-Roddick era, Isner's career is mediocre at best. 

Brad Gilbert, who reached a career-high No. 4, played among icons of American tennis, including John McEnroe, Pete Sampras and Andre Agassi. He won 20 titles and reached the quarterfinals at Wimbledon and the U.S. Open. Yet these days Gilbert gets more accolades for what he's done as a coach and commentator.

Unlike compatriots Donald Young and Sam Querrey, who often flame out, Isner rarely stinks up the joint. He's like that reliable Buick sedan, dependable and American-made. Sure, it won't turn heads like some of the sportier and faster foreign models. But it will keep you rolling.  

Isner also takes seriously his place as the American No. 1. When he defeated Gael Monfils at the 2013 U.S. Open, Isner expressed disappointment about the New York crowd getting behind the flamboyant Frenchman. 

After the match Isner told reporters, "I was a little bit disappointed in that, actually. Not going to sugarcoat it.  It was certainly, if I was playing him in France, it certainly wouldn't be like that."

Last year, Isner told ESPN he was unhappy about the Citi Open putting his match on an outer court instead of in the stadium. "When I'm playing in the States, I want to play on center court; I want to have the crowd on my side...I'm the No. 1 American."

Right now there's no definitive successor to Isner. Steve Johnson, ranked No. 43, is the second-highest ranked American. 

Unless Isner wins a Slam or two, he will fall short of Hall of Fame credentials. He may be best remembered as the bridge between the post-Roddick era and whatever comes next.

His serve will stand out and he may even walk away with some serving records.

Isner's legacy will probably play out like his career. Whether ranked as high as No. 9 or as low as No. 24, he's been the American No. 1 for a while. Unless something dramatic changes, until he retires, No. 1 is where he'll stay.