how to buy tadalafil online

Tennis: The Aggressive Margin

February 3, 2010
By

Well, it’s over, and I miss it already.

Seems like only yesterday the first grand-slam of 2010 was getting underway, and now here we are, two weeks later with a new women’s champion (congratulations Serena, even if I wasn’t rooting for you.  You dug yourself a deep hole with your deplorable conduct at the US Open last fall, and I ain’t talkin about the outburst; I can kinda sorta understand that.  I’m talking about the complete and utter inability to take responsibility for how you handled your post-match interview.  Anyway, I don’t have it in me to forgive and forget.  Not yet anyway.), and a new men’s champion, the ever impressive Roger Federer, and undisputable, GOAT! (“Greatest of All Time”)

I waited the entire tournament to find THE match to tell ya’ll about this “Aggressive Margin” thing, but there weren’t any that fit all my criteria, so I picked a match that was really, really close.

Rewind the clock to Thursday, Jan 28th; the Serena Williams Na Li match (interesting thing I learned: in China, everyone is introduced by the last name first, first name last, so to be politically correct, as well as polite, the announcers were referring to Na Li as “Li Na”, which rolls off the tongue a little easier anyway)

As you can see by the score (7-6, 7-6), Serena won a close one, with both sets going to tie-breakers.  So, how and why did Serena win?  Well, for that, we need to take a look at the match statistics:

Serena Na Li
1st Serve % 49 of 82 = 60 % 68 of 99 = 69 %
Aces 12 1
Double Faults 2 6
Unforced Errors 24 38
Winning % on 1st Serve 42 of 49 = 86 % 46 of 68 = 68 %
Winning % on 2nd Serve 15 of 33 = 45 % 14 of 31 = 45 %
Winners (Including Service) 33 21
Receiving Points Won 39 of 105 = 37 % 25 of 84 = 30 %
Break Point Conversions 1 of 9 = 11 % 1 of 4 = 25 %
Net Approaches 8 of 13 = 62 % 5 of 9 = 56 %
Total Points Won 96 85
Fastest Serve Speed 188 KMH 204 KMH
Average 1st Serve Speed 172 KMH 155 KMH
Average 2nd Serve Speed 137 KMH 144 KMH

OK, so a few things stand out: First, look at the number of aces.  Serena’s serve was absolutely THE most important factor in this contest, and you’ll notice that she only gave Na Li four chances to break in the entire match.  Na Li, conversely, gave Serena nine chances to break, though both were only able to capitalize on one of those break opportunities.  This ought to tell you what a tough, defensive fighter Na Li is; she wasn’t able to dominate or dictate play with her serve, but she managed to hang in there and hold serve just as often as Serena, who arguably has one of the best, if not THE best serve in the women’s game.  So, serves were critical.  What else?

Well, take a look at unforced errors.  Serena had 24, Na Li had 38, a 14-point differential.  And yes, I mean 14 points.  If it takes 4-points to win a game, that could have been equal to three and a half games!  And yet, it wasn’t; again, testament to the fierce defensive play exhibited by Na Li.

Before we move on, it’s worth commenting on how points are scored in tennis.  Each time a game starts, there’s a point up for grabs, and somebody’s getting that point.  It’s not like any other sport where you can punt, or leave runners on base, or miss a 3-pointer, only to have the other team rebound and switch from defense to offense.  No, in tennis, there is always, always a point on the line.  There’s no clock to run out, and nowhere to hide, and eventually, somone’s gonna get it.  Unforced errors then, are literally gift points.  If you’re too busy thinking about how pissed off you are about netting that last forehand that you forget to watch the ball on this forehand…the one that’s headed to your racquet at this particular moment in time…you may very well net another forehand, for lack of focus.  And every unforced error you make is a gift you give to your opponent, and every unforced error they make is a gift to you.  Clearly then, the goal is to make as few as possible.

Another way to score points is by simply hitting a ball that your opponent cannot get to.  They’re in the ad court, you smoke a screaming forehand into the (open) deuce court, and if they’re not quick enough to track it down, you get a winner.  And yes, that works both ways.  It’s funny how unreasonably huge the 1053ft2 of court-space feels on your side of the net, and how ridiculously small the 1053ft2 of court space appears on your opponents side of the net.  It feels like you’re trying to defend an open court the size of Omaha whilst trying to hit your ball into a court the size of a small throw rug.

Anyway, that’s it.  There are two ways, and only two ways, that a point ends in tennis: either you score (winner by you or unforced error by your opponent), or your opponent scores (I’m assuming I don’t have to explain the counterexample at this point), but regardless, somebody is going to score.

Well…almost; there’s actually a bit more to it.  For this next part, you’ll need to refer to the match stats.

Q: How many winners did Serena hit?  A = 33.  And how many gift points did she receive from Na Li?  A = 38 (the 38 unforced errors committed by Na Li) for a total of 71 points.

But wait a second…the stat sheet shows that Serena scored 96 points?  Where’d those extra 25 points come from?

Good question grasshopper; welcome to the Aggressive Margin!

I first read about the Aggressive Margin in the New York Times “Straight Sets” blog, in a post titled “Behind the Numbers of a Federer Victory

“…the Aggressive Margin is…“a composite statistic that combines how a player wins and loses all points into a single index. Understanding this one key number allows any player to see exactly what happened in a given match, and how. Basically all tennis points end in one of three ways: winners, unforced errors, or forced errors. The Aggressive Margin puts all three together into a comparative measure…”

“So how do we calculate the Aggressive Margin? First for a given player, we add up the total points won through winners and the total points won on forced errors. Then we subtract the total number of unforced errors. The difference is the margin of points the player won by aggressive play. This is the Aggressive Margin.”

Forced errors?  Correct.  If Roger Federer hits a 97mph forehand directly at your feet, the chances of you doing anything meaningful with that ball are slim to none.  Chances are that you will produce an error, but it’s not classified as an unforced error; there was simply nothing you could do about it.  Instead, it’s called a “Forced Error”, which the match stats don’t track, for some reason I’m not aware of.  Regardless, now that we know of it’s existence, we can derive it from the stats on hand to peel back yet another layer of the match, and glean a little bit more info about who played more aggressively.

Here is another look at the Serena/Na Li match, this time with the Aggressive Margin revealed.  I’ve highlighted the relevant statistics from which the AM is derived:

Serena Na Li
1st Serve % 49 of 82 = 60 % 68 of 99 = 69 %
Aces 12 1
Double Faults 2 6
Unforced Errors 24 38
Winning % on 1st Serve 42 of 49 = 86 % 46 of 68 = 68 %
Winning % on 2nd Serve 15 of 33 = 45 % 14 of 31 = 45 %
Winners (Including Service) 33 21
Receiving Points Won 39 of 105 = 37 % 25 of 84 = 30 %
Break Point Conversions 1 of 9 = 11 % 1 of 4 = 25 %
Net Approaches 8 of 13 = 62 % 5 of 9 = 56 %
Total Points Won 96 85
Fastest Serve Speed 188 KMH 204 KMH
Average 1st Serve Speed 172 KMH 155 KMH
Average 2nd Serve Speed 137 KMH 144 KMH
Points gained by forcing errors 25 40
Winners 33 21
Aggressive Points 58 61
Aggressive Margin 34 23

Yes, there are lessons to be learned from this, simply from learning what factors are involved in calculating the Aggressive Margin.  First, you must, Must, MUST keep your unforced errors at a minimum.  Second, you must, Must, MUST play aggressive enough to force your opponent into making errors.  However, you’ve got to be careful!  As Agassi said,

Tennis is about degrees of aggression. You want to be aggressive enough to control a point, not so aggressive that you sacrifice control, and expose yourself to unnecessary risk.

And third, you must, Must, MUST stay focused, and finish your opponent, which ain’t easy.  You could be ahead 5-0, serving at 40-0, and still lose the match if you lose focus.  Remember: There’s no such thing as a “lead” in tennis.

Anyway, to calculate your AM for any given match, you add up your winners, and then add your opponents forced and unforced errors, which give you your total points won.  Next, just focus on the winners you hit and the forced errors you created (these points are earned by playing aggressively).  For Serena, this translated into 58 “aggressive points” in her match with Na Li.  Subtract the unforced errors you made (points you gave to your opponent) from the Aggressive points you scored, and what’s left is the margin of aggressiveness.

There’s a ready-made template available on Google Docs, if you’re interested.  All you gotta do is copy the match stats from the web, and then paste them into the spreadsheet, and it figures it all up for you.  As you can see, Serena thoroughly outplayed Na Li, in most every category.

Does the AM always reveal the better player?  No.  Consider last year’s epic final between Nadal and (who else) Federer.

Using the match stats from that match, and the template I’ve provided, you can see that not only did Federer score more points than Nadal (1 more point, but still…), he played more aggressively as well.  So why’d he lose?  Because what the AM doesn’t show you is when those points were scored.  A point scored at 15-15 isn’t nearly as critical as when it’s game point.  Or match point.  Or championship point.  Although Federer played tough the first 4 sets, the wheels came off in the 5th, and Nadal was able to wrest it away from Federer.

Anyway, like they say, “Tennis!”

Share

Tags: ,

2 Responses to “ Tennis: The Aggressive Margin ”

  1. Hollywood Hood on February 3, 2010 at 10:36 pm

    Damn Smarty – You need to send that over to our pal at the NY Times….knowing the AM is one thing, teaching it is quite another…If you calc the % of Frothy fans that are tennis fans x the % that are statistics fans you get… Ummm… you get …me. Great article, boost it over to tennis/gambling site….see you on da courts!

  2. Mr. Smarty Pants on February 4, 2010 at 12:14 am

    Check it out Horton…if you even up the “Aces” category for the Serena/Na Li match, giving them the same number of Aces (doesn’t matter whether you subtract from Serena’s column or add to Na Li’s), the winners for both end up the same at 33 each. The number of points are the same; 96 each. And, the aggressive margin is the same, at 34 points each. The only unequal thing about the match was Serena’s serve; that’s what won her the match, and ultimately, the championship.

    BTW, I actually *did* send the link over to Geoff MacDonald (contributor to the “Straight Sets” blog at the NY Times), and he wrote back saying, basically, “Thanks, enjoyed the article”. Pretty cool. He’s also the same guy that wrote the article about “finishing off an opponent”, which is worth reading as well.

    Thanks for the props dood. And sharpen your sword; we shall enter combat in 3 days time!

Archives