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Understanding Match Statistics

The Aggressive Margin

 John Yandell  

Still Photos by J Gregory Swendsen

Agassi VS Sampras in Other Big Matches

Now let’s compare the Aggressive Margin from the 2001 Sampras/Agassi match to some of their other big matches over the years, for example the famous 1995 U.S. Open final also won by Pete in 4 sets. At the time the match was considered one of the greatest matches of all time, but statistically the 2001 match was played at a far higher level. In fact the Aggressive Margin this year was double or more for both players. 

Pete won in 1995  averaging +12.5/set for 4 sets. Andre again just about 3 points a set behind at +9.75/set.   Note the difference this time, less than 3 points a set.  

How about the 1999 Wimbledon final won by Sampras in 3 straight sets? Again, statistically it was played at a high level, but nothing like 2001. In that match Pete finished at +18/set and Andre was at +11/set. This match was not as close and the stats showed it, with Pete winning 7 more points a set than Andre.  

Those three  matches were all won by Pete. But what happened in some of the big matches won by Agassi over the years? Interestingly the real difference appears to be in Pete’s level of play. Statistically, Pete’s margins were much lower in the matches he lost, while Agassi’s were closer to the same.  

In the 1995 Australian Open, Andre defeated Pete in 4 sets. His average Aggressive Margin was +13.25/set. Pete’s was at just +9.5/set. This was less than half of the 2001 U.S. margin for Pete.  

Another Agassi victory came in the 1995 Canadian Open, just prior to the 1995 Open final. In a 2 out of 3 set match, Agassi won in 3 sets, with an Aggressive Margin of +9.3/set. Pete’s Aggressive Margin dropped all the way +6.6/set.   

When we look at the Aggressive Margin over the course of the rivalry we see that in terms of the numbers, Pete’s level of play basically dictates the outcome. Statistically speaking, it seems that Pete at his best simply has the ability to play a slightly higher level of tennis than Andre—that is the ability to win a few more points outright through aggressive play. In the matches won by Andre, Pete’s Aggressive Margin drops by half or more from his highest totals to under +10/set.

The irony of course is that +10/set is still a fantastic number. It’s probably good enough to win the majority of pro tour matches. But Pete at his best can command slightly more firepower than Andre. If he does, then he wins, regardless of Andre’s level of play.  

The 2001 Final broken Down by Stroke

Now let’s go back to the 2001 final and try to go deeper and see exactly how both players generated those fantastic margins, and why Pete’s was slightly higher. Let’s break down the Aggressive Margin stroke by stroke. 

First let’s look at Pete. It’s not a particularly deep insight to say Pete’s serve is a formidable weapon. How formidable? Of the 153 points he won by aggressive play, nearly half  were on unreturnable serves. He also won almost 50 points at the net, with an amazing 25 forehand volley winners or forced errors. But what is surprising is how well his groundstrokes matched up against Andre, particularly his often maligned backhand, something we discussed extensively in Part 1.  

Note that Pete had 22 winners or forced errors on his backhand, actually more than on his forehand side. This was actually the same number of backhand winners as Andre, although Andre did make far fewer backhand errors.  

Now let’s compare that to Andre. As we also noted in Part 1, Andre served amazingly well himself, with 35 winners or forced errors. As you would expect, he did win the overall ground battle, including an amazing 45 winners or forced errors with his forehand.

The bottom line was Andre served better than expected, and he won the battle off the ground. This just wasn’t enough to overcome Pete’s serving, his net play, combined with his own stronger than expected groundies.  Remember we are talking about just 3 points a set. Cut Pete’s groundstroke winners in half or eliminate just a few of those incredible volleys and the outcome would have been different.  

Interestingly, this is exactly what we see in the two charted matches mentioned above won by Agassi, the 1995 Australian and 1995 Canadian Open. Let’s compare groundstrokes in those matches to the 2001 Open.  

At the 2001 Open Pete had 37 groundstroke winners and forced errors and 36 unforced errors. His Aggressive Margin for the match off the ground was only +1, but that was still a lot of winners and just good enough combined with his fantastic serving.

At the 1995 Australian, however, he had only 26 winners and forced errors off the ground and 41 unforced errors, also in 4 sets. So his Aggressive Margin off the ground there was negative at –14 for the match. He also won far viewer points outright at the net: only 18 in the Australian final versus 47 at the U.S. Open. This brought his Aggressive Margin down to +9.5/set, as noted above.

Agassi didn’t hit as many winners in the Australian match, but he didn’t make nearly as many errors as Pete.  Unlike Pete, he was positive in all categories and finished with an Aggressive Margin of +13.25/set. These shifts were the difference in the match. Note that again the winner was decided by around 4 points a set!

The stats told a similar in the 1995 Canadian final won by Agassi in 3 sets. Pete had 16 backhand errors and won only 5 points with winners or forced errors. His Aggressive Margin on his backhand was –11 for the match. This was actually greater than the total point margin, since Agassi won only 8 more points over three sets.

So with these two great champions it boils down to how well Pete serves, and how close he stays with Agassi off the ground. If Pete serves well and keeps his winners and errors off the ground about equal, he tends to win.  Admittedly Pete’s game is riskier and naturally prone to more ups and downs. Still it’s fascinating to compare how the strengths and weaknesses of these great champions match up, how small shifts of only a few points a set determine the outcomes—and to see where those shifts occur.

How much do you know about where you are winning and losing your own points? Where is your game positive, where is it negative, and how does it shift over time? Are there magic numbers at different levels that add up to winning tennis? More on this in the coming articles.

Your comments are welcome. Let us know what you think about John Yandell's article by emailing us here at TennisONE.  

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