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Old 01-06-2013, 02:09 PM   #23
Join Date: Dec 2006
Posts: 5,532

Another great example of clashing styles: 1988 USO final between Wilander and Lendl. Wilander had approximately 35 winners and 35 errors. Lendl was at about 85 winners and 85 unforced errors. The match went down to the wire, 6-4 in the fifth.

I'm taking those stats from memory, but yes, each player's winners and errors were almost exactly equal. Only the totals between the players differed, and by a lot: you can't get a greater contrast in styles than those two men.

Wilander, despite being nowhere near as aggressive as Lendl, is represented accurately in the Aggressive Margins. He had 13.8%, Lendl 12.2%.

Originally Posted by Moose Malloy View Post
I had Becker with 7. I know that's unofficial, but I'm curious what the AM would be in that match. That goes for any of our stats where we calculated UE's(Laver-Ashe etc)
You could just mention that the AM was calculated with unofficial stats when posting some of these(I doubt Laver ever played a match where officials were calculating winners/ue's, may as well use ours just for fun)
If you add those 7 to Becker's 15 df's, his total UE would be 22. Sampras had 7 UE of every kind (all 7 were DF's), per official sources including NBC.

So, if Becker has 22 UE's, Sampras' AM is 44.3%, Becker's 32.1%.

If you give Becker more than 22, Sampras' AM would go down.

If Becker goes down below 22, Sampras' AM would rise. Becker has at least 15 UE's (his df's), so Sampras' ceiling in this match would be 47.2%.

I would be wary of comparing AM's across eras if we go back as far as Laver. (Even comparing against the Sampras era could be problematic). But sure, it's worth doing.

Originally Posted by Moose Malloy View Post
I guess the winner # isn't really necessary in calculating any AM's, just the UE count for both players.

Originally Posted by fed_rulz View Post
Here's a question: are service winners included in the opponents forced error column? IMO, this method would be more accurate if serve-related stats are excluded in calculating the AM.
The AM takes into account every point in the match, so quick answer is yes. The AM is calculated by taking the total number of points that a player won, and subtracting the points that he won through his opponent's unforced errors. The result, mathematically, must be the points that he won aggressively (his Aggressive Points), either through clean winners/aces or by forcing his opponent into errors.

The last step is to take those Aggressive Points and compare them to the same player's Unforced Errors. The final result is the Aggressive Margin.

I can't imagine how this method would be more accurate if service winners are excluded. It MIGHT become more accurate, in that case, if you're looking for levels of play apart from service. But I have doubts about that, because the serve is connected to everything. Not every point in tennis has a forehand, but every point has a serve.

Moose and I have seen matches in which winner/error differentials -- because they only use unforced errors -- give a distorted picture of the match. The loser will come away with a higher winner/error differential, for example. But the loser, in these examples, definitely lost more than 50% of all the points played (we know because we counted). That's how you know that the victor must have pulled ahead in the missing category of forced errors.

And when there is a large difference in the quality of two players' serves -- or a large difference in the quality of their returns -- one player will get a lot more free points by forcing errors on the return. Those errors are not aces, and not outright unreturnable serves, so they don't show up in the typical winner/error stats. But those errors often make the difference.

So I'm not sure what you're trying to isolate by taking out the serve. You might isolate something, but total level of play definitely has to include everything.

Last edited by krosero; 01-06-2013 at 02:24 PM.
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