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The Aggressive Margin and Your Game

 John Yandell

Can the average player learn anything from match statistics? The answer is statistics can tell you things about your game you can’t learn any other way. Not all statistics are equally valuable. And it is more than possible to create statistical overload—just check out the websites of the Grand Slam events if you want to be buried in statistical information. 

But focusing on the right statistics can reveal exactly how and why you are winning or losing matches and what options you may have for improving. If you are willing to face the truth, statistics can open a whole new path to reaching your competitive goals. Let’s see what statistics saw about a wide variety of matches below the pro level.           

The first two articles in this series explained two key statistics that are required to really understand match outcomes: the Forced Error and the Aggressive Margin. Ironically, these statistics are probably unfamiliar to most players, since aren’t typically tracked either by television or official tour match statistics. There is a glut of information—too bad it doesn’t include these key numbers. So let’s review what they are and why they are so important in understanding matches. 

A Forced Error is an error that stems from pressure created by the other player’s ball. This is different from the more familiar concept of the Unforced Error. An Unforced Error is a mistake that a player makes on an easy or routine ball—the error stems from the player’s inability to execute what should be a simple stroke or return.   

A player generates a Forced Error through pace or location, or a combination of both, say for example, a deep, high velocity crosscourt forehand. The other player reaches the ball on the run and takes something resembling a normal swing, but is unable to control the ball and return it into the court. Even though the player had a chance to make a return, the error was “forced” by the opponent’s aggressive play.

Forced Errors are critical statistics because they account for up to half or more of the points in most matches.  Without Forced Errors, sometimes TV statistics don’t make sense. Sometimes a player with fewer Winners and/or more Unforced Errors still wins the match.   

The Aggressive Margin

So tracking Forced Errors is critical. Once we start to track Forced Errors we can then combine them with the better known stats of Winners and Unforced Errors to calculate the second key stat, what is called the Aggressive Margin.    

The Aggressive Margin is the total of a player’s Winners and Forced Errors minus his Unforced Errors. For example, let’s say a player hits 10 Winners and generates another 10 Forced Errors. That’s plus 20. Let’s say he makes 10 Unforced Errors, that’s –10. Subtract the Unforced Errors from the Winners and Forced Errors (20-10 = 10.). That’s an Aggressive Margin of  +10. 

Whether you're a top pro like Andre Agassi, a high level tournament player, or a club player, keeping track of your aggressive margin can mean the difference between victory and defeat.

The Aggressive Margin gives us an instant understanding of how a given match was really won or lost. It can be calculated for an entire match and also on a set by set basis. The Aggressive Margin can be a positive or a negative number. It shows whether a player is playing positive tennis, or simply relying on his opponent to make more errors than he. 

In the first two articles we saw how the Aggressive Margin works in pro tennis and how it could take us inside the Sampras/Agassi rivalry and explain why and how Pete squeaked out the 4-set win at the 2001 Open quarterfinal. 

As I wrote, that match was the highest quality pro match I’d ever charted, in terms of the stats and pure shot making. Over 4 sets, Pete had an average Aggressive Margin of +24.25. Andre’s Aggressive Margin was +21.25. That meant that over 4 sets, exactly 12 points separated these two great players. 

Over 75% of the total points were decided by pure shot making—and over a third of these points were Forced Errors. That’s about as close to perfect tennis as human beings can play. But what about the rest of us? Can we really expect to play with these kind of positive margins? 

The Aggressive Margin and the Club Player

Surprisingly, the answer can be yes! The Aggressive Margin reflects the quality of the exchanges at the specific level of the players involved. That’s what so great about it. The Aggressive Margin is not an absolute. It’s a relative measure that reflects the quality of the points and shotmaking between particular players at a particular level in a particular match. 

So let’s look at some numbers from matches at a range of levels. Senior tournament tennis, and then class or NTRP matches ranging from the 4.0 to 5.5 levels. 

Interestingly some of the highest level matches I’ve ever charted have been in seniors’ tennis. The quality of the shot making and the percentages of winners actually approaches the levels of the best Sampras/Agassi matches, and exceeds that of the majority of tour matches. 

It’s important to note I’m not saying these players are BETTER than Pete and Andre. They are, obviously, not generating the same levels of pace. But what the stats do show is that these players are playing very high level statistical tennis. They are playing within their own capabilities and using their shotmaking to set up an execute winning points. 

For example, let’s examine the final of a men’s 45s tournament  between two highly ranked national players, both of whom played serve and volley style. Player A won the match in 3 close sets with an average Aggressive Margin of +20/set. This was only slightly better than player B, who had an Aggressive Margin of +17.5. 

What was especially interesting was that both players were “positive” in literally every category of shot making—serves, groundstrokes, and net play. This was a beautiful example of skilled players playing their best tennis. Both executed their shots when they had opportunities. Both were extremely parsimonious with their unforced errors. It was true high percentage tennis. 

Here is the Aggressive Margin by shot over the match:   

In reality the match was actually closer than the Sampras/Agassi match at the 2001 Open. Only 2.5points per set separated the players. Put another way, Player A won one more point every 4 games than Player B!    

These players were experienced former college and lower level pro players who were now competing in their forties. But what about players closer to the average level of club tennis? 

Surprisingly, I’ve found that this basic principle of positive percentage tennis seems to be virtually universal among successful players at all level. Players who win at the 4.0 level and up seem to put up positive Aggressive Margins. They understand their shot making capabilities and use them to set up and execute winning point patterns. 

This conclusion is based on a few dozen matches I’ve charted over the years for players I knew, played with, or coached. It would be very interesting to develop a large data base of match stats for every rung on the NTRP ladder. What are the margins you need to be successful at everything from 2.5 to 5.5 tennis? But the information we do have all points in the same direction—winning players play positive statistical tennis. 

I’ve found this to be true even for many players that are commonly perceived as “pushers.” Yes, their consistency forces opponents into multiple errors, but they combine this with just enough judicious shot making of their own, and this is often the final nail in the coffin in a given match. 

The final of a club 4.0 singles tournament is a good case in point.

Player A was the most feared “pusher” at the club. A short guy, a runner, with funky strokes and no serve to speak of. Player B had classic strokes, some real power off the ground, and a seemingly good serve, with decent velocity.  

Player B charged into the final, where as Player A had had some long, difficult matches. But in the final Player A, destroyed player B 6-1, 6-3, and it wasn’t really that close. The Aggressive Margin by stroke tells the tale.

Note that Player A , was positive or even on every stroke except his forehand. He combined this with some well-timed net approaches where he was actually +8 for the match. For the match he stayed in positive territory at +3 a set.  

Player B on the other hand destroyed himself off the ground. This started when Player A floated almost every first serve return in, giving away only 3 free points over 2 sets. So virtually every point started as a groundstroke rally. In attempting to counter the consistency of his “pusher” opponent, Player B made an incredible 41 Unforced Errors in only 16 games. Believing that his groundstrokes were the strength of his game, he continued to hammer away, no matter how many balls came back and how many errors he made.   

Player A, on the other hand balanced his incredible baseline consistency with over 30 net approaches—better than 2 net approaches a game! And he won over 60%. This combination proved tactically and psychologically lethal. Just when Player B was sick to death of rallying, there was the “Pusher” at the net hitting a winning volley, or drawing another groundstroke passing shot error.   

Player A intuitively understood how to get the most out of his abilities and found a way to hit enough winners to make his overall numbers positive for the match. His play was no fluke—he also led the club’s league team to a USTA national 4.0 championship match.   

What could have Player B done differently? He went to the net 20 times and won over half of them, but that was still fewer net appearances than the alleged “pusher” Player A. Given his unforced errors in the backcourt, he might have swung the odds in his favor, but the bottom line, he just wasn’t that comfortable there.   

He didn’t have a plan “B”—or put another way, an alternative ability to play positive points. He just liked to serve hard and try to hit the ball hard off the ground, and he stuck with what he was comfortable with—and lost badly.  

Let’s look at a match at a slightly higher level a 5.0 club final. This match was also a classic confrontation in style. A pure serve and volleyer versus a pure power baseliner. Player A, the baseliner, won 7-5, 6-3, with an average Aggressive Margin of +10 /set. Player B, the serve and volleyer was +1.5/set  

In this case both players had well-developed styles, and both players were able to play positive tennis. But the player who was able to play higher level statistical tennis won. In the exchanges at the net, Player A’s returns and passing shots were too good for Player B’s volleys. And on his own serve Player A kept Player B in the backcourt and forced many errors.  

Here’s what the numbers show:

Obviously Player A dominated from the backcourt. He was +20 for the match from the baseline, versus a whopping –14 for Player B. Player B had some success with his serve finishing at +8 and was +9 at the net, but this barely overcame his unforced baseline errors. He went to net 65 times in the match, but won barely 50% of the points. Player A was able to hit an amazing 22 passing shot winners, so that was the story.  Strength versus strength, in this particular match up, the baseliner did better in the exchanges than the serve and volleyer.  

As we saw in our analysis of pro matches, the player with the higher Aggressive Margin wins virtually every match. It’s not just the “big” points, it’s the total number of points that count. Good players recognize this, consciously or not, and find ways to win points consistently over the course of a match.  

It’s one thing to play percentage tennis in your own style and lose to a better player, it’s another thing to just lose by giving the match away trying shots that are beyond your capability. Even in this case, though I did feel that Player B missed one opportunity. Player A was clearly not comfortable at the net. Had Player A hit a series of drop shots on Player A’s service games—he could have actually done it on either of his serves--would have that have changed the nature of the exchanges? It was really the only other possible option—but that’s the point—could he have found a way to shift the stats in his favor?  

Note that for Player A, his Aggressive Margin of +10/Set is a borderline pro level number. That I think is one of the inspiring things about the Aggressive Margin. We may not be able to serve at the speed of Pete Sampras or hit forehands like Andre Agassi, but whatever our level we can learn to play the percentages and generate positive Aggressive Margins, just like the pros, and sometimes equaling or even exceeding their margins.  

Although it would be great to compile a data base of a few hundred matches at all levels, here are some representative matches I’ve charted over the last few years, (including the one’s discussed above) mostly tournament finals or semifinals that give an indication of the level of play of the winning players in various divisions.  

Although there is a wide range in the Aggressive Margin, it’s interesting that in virtually every match I’ve charted involving successful players at a given level, the Aggressive Margin is positive, even at the 4.0 level (admittedly for a national caliber 4.0 player.)  

Again, what we find is that at any given pace of the exchanges, positive statistical tennis is the key to victory.  The best 4.0s, 4.5s, 5.0s, etc will win more points than they lose by playing correct patterns and making high percentage shot execution.

The message seems obvious. Developing the ability to win points through positive shot making is the key to winning—and making sure you’re positive shot making exceeds your unforced errors. Unless you can play positive statistical tennis on a consistent basis, your only hope is that your opponent has worse negative numbers than you. This explains why some players win one match, think they are playing great, and then are mystified when they play exactly the same way against another opponent and lose badly.  

As I mentioned in a previous article, I once charted a match for a girl on my high school team, which she won easily in straight sets. She was happy and thought she had played well. But the numbers showed otherwise.  My girl actually had an Aggressive Margin of -17 for the match. She won only because the other girl was –35! Think about it. At 4 points per game that’s over 8 games in 2 sets that the girl just handed my player.   

In the next articles more on charting junior matches and what that shows, as well as how to chart your own matches and develop your own player profile.  

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For more information on John Yandell's Advanced Tennis Research Project, click here.

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