When I joined TF there was a lot of discussion going on in this forum about all sorts of statstic stuff. I've always found it interesting but sadly it has become a whole lot less over the last couple months - mainly, I think, because Vikapower isn't that active around here anymore. So I try to put some life back into this thread (Well, Howard made a start already
What I find annoying about match statistics is that they don't show the number of Forced Errors (FE). For a player like Julia this is an important figure because it further highlights how many points she actually won by aggressive play. In pretty much all statistics, however, you'll only find a winner (W) and unforced error (UE) count (apart from serve % information). The W/UE ratio is supposed to show then whether a match was good (>0) or bad (<0) - which is quite useless IMO.
Thankfully Vikapower added the FEs for Julia's matches - and not only that, he also added the aggressive margin (AM) (at least used to do it until April 2012). The AM now combines all W, FE and UE into a single index ((W+FE)-UE) - see also here
). It basically shows the "effectivity" of the game of an aggressive player (like Julia) during a match.
No doubt, the AM is a lot more informative than the W/UE ratio. However, as the latter, it isn't very specific. It's perfectly possible that you get the same AM number for a match score of 6-2 6-2 and, say, 6-1 1-6 6-1. So, the problem is that it can't tell you anything about what actually happened in a match.
You get a more detailed picture when you look at the AM for each game. I did that for 2 matches of Julia (against Rezai and Arvidsson - both 2012) though it was quite time-consuming..
Anyway, for the Arvidsson match the result looked like this:
There are 2 x-axes - the upper one is showing the number of games, the lower one the score for each game. On the y-axis I put the AM (-5 to 5)
The red line illustrates Julia's AM per game.
The yellow line shows Arvidsson's AM per game (only shown for the 2nd set).
The magenta line is basically a more detailed version of the red line for a single game.
An AM per game > 0 means that the player played her game pretty effectively.
An AM per game < 0 means the opposite (of course
So, what do we actually see here? When we look at the 1st set we see that Julia was able to put on a quite dominant performance. There is a slump in the 2nd game but after that her level of play stayed high. The AM never dropped below 1. Well, actually it did shortly in the 7th game - and this is what I highlighted with the magenta line:
What happened in that game? Up until 30-30 both players took turns at hitting UEs which resulted in an AM of -2 (in this case for each player). Arvidsson won the next point (FE) which gave her the chance to break. Now Julia not only saved that BP with a winner, she also won 3 of the next 4 points by either a FE or a winner and eventually converted her 2nd setpoint (equated to an AM of 3). The important thing to note here is IMO: When she faced a bp she was able to stay focussed and to win point by point through aggressive play. You could see this as a clear sign of mental strength.
Just to make things clear: While the red line for the 7th game indicates a throughout solid display from Julia (AM=1), the "reality" (magenta line) looked a bit different: First part of the game was weak (AM=-2), second part was really strong (AM=3) (The sum of AM -2 + 3 = 1 is again reflected in the red line).
In the 2nd set Julia was able to keep her momentum. She broke Arvidsson in the 1st game and had a love game right after that.
In the beginning of the 3rd game she continued to play very dominantly. She hit 2 winners and a FE to earn herself 2 BPs. However, she couldn't convert any of them, hitting two UEs instead. Now the momentum was gone. Arvidsson eventually held after Julia hit another 3 UEs.
In the 4th game she still couldn't find her rhythm. She made 3 UEs in a row and faced 3 BPs at 0-40. At this point, however, she made a strong comeback saving all 3 BPs (with 2 winners and 1 FE). She eventually held serve for 3-1.
Julia now gained momentum again but so did Arvidsson. Until this point the match had been all about Julia. Arvidsson barely had hit any winners, FEs (or UEs) during the 1st set and the beginning of the 2nd set. That changed with the 5th game. Arvidsson suddenly played also more aggressively and she did well. The yellow chart is reflecting this. One could say the overall quality of the match improved in the middle of the 2nd set with both players hitting more winners and FEs than UEs. The exception is obviously the 7th game but IMO Julia just tanked this one to save energy for the rest of the match. The quality remained high until the last game when Arvidsson seemed to have given up.