{"id":425,"date":"2011-08-07T16:48:19","date_gmt":"2011-08-07T20:48:19","guid":{"rendered":"http:\/\/heavytopspin.com\/?p=425"},"modified":"2011-08-07T16:48:19","modified_gmt":"2011-08-07T20:48:19","slug":"do-points-get-shorter-as-the-match-progresses","status":"publish","type":"post","link":"https:\/\/www.tennisabstract.com\/blog\/2011\/08\/07\/do-points-get-shorter-as-the-match-progresses\/","title":{"rendered":"Do Points Get Shorter as the Match Progresses?"},"content":{"rendered":"<p>On Friday, some interesting ideas were batted around in the comments to my post on the 61-shot rally. \u00a0One of the simpler ones boils down to the question that titles today&#8217;s post: <strong>Do points get shorter as the match progresses?<\/strong><\/p>\n<p>Two forces seem to work in opposite directions:<\/p>\n<ul>\n<li>As players get used to each other&#8217;s games (and specifically their serves), more balls get returned. \u00a0Before looking at the numbers, I would&#8217;ve bet that this was the case, meaning that aces and service winners decline as you go deeper into a match.<\/li>\n<li>The longer the match, the more tired the players. \u00a0Tired (or even slightly injured) players take more risks and probably have shorter rallies.<\/li>\n<\/ul>\n<p>To answer the question, I looked at rally lengths shown in Pointstream at the last three grand slams. \u00a0That gives us close to 250 men&#8217;s matches, all best-of-five sets.<\/p>\n<p>The short, unsatisfying conclusion is: <strong>The results are mixed.<\/strong>\u00a0 At Wimbledon and Roland Garros, rally length increased later in matches&#8211;as much as 10% in London and 20% in Paris. \u00a0At the Australian Open, the result was the exact opposite, with rally length decreasing substantially. \u00a0Perhaps rally length increases in most cases, <em>except<\/em>\u00a0when it is extremely hot or the players are not yet in top shape. \u00a0The blistering heat in Melbourne is certainly a plausible reason for a decrease in rally length.<\/p>\n<p>As we&#8217;ll see when we move into more specific findings, the results get even more jumbled. \u00a0It seems that points <em>generally<\/em>\u00a0get longer as a match progresses, but not necessarily because players read and return serves better. \u00a0While rally lengths increase, the number of one-stroke points (aces, service winners, service return errors) often increases, as well.<\/p>\n<p>Follow the jump for my methodology and full results.<\/p>\n<p><!--more--><\/p>\n<p><strong>Methodology<\/strong><\/p>\n<p>As noted, we have about 250 matches to work with. \u00a0I split each match in half&#8211;one half for each server&#8211;so that I could treat, say, del Potro&#8217;s service points differently than Olivier Rochus&#8217;s service points.<\/p>\n<p>For each &#8220;half-match,&#8221; I broke it down into 30-point segments. \u00a0Thus, if Delpo hit 90 serves, the first segment was his first 30, the second segment was his second 30, and so on. \u00a0(I threw out some serves when there was a &#8220;leftover&#8221; segment of 15 serves or less.) \u00a0Then I compared the rally lengths in each of those 30-point segments. \u00a0I converted the average rally lengths of each segment to a ratio, so we call the first segment &#8220;1&#8221;, then if the rally length increased, the second segment might be &#8220;1.12.&#8221; \u00a0This puts all servers on the same scale.<\/p>\n<p>Once that was done, I averaged all the ratios. \u00a0There was plenty of variation, with ratios anywhere from 0.6 to 1.5, but the averages never strayed too far from 1. \u00a0I went through this process for three statistics:<\/p>\n<ul>\n<li>Average rally length of all points. \u00a0(Aces and service winners have a rally length of 1; double faults, 0.)<\/li>\n<li>Average rally length of points where the service return was in play. \u00a0(I thought eliminating shorter points might be valuable.)<\/li>\n<li>Percentage of &#8220;short&#8221; points. \u00a0(When the returner didn&#8217;t get the ball back in play.)<\/li>\n<\/ul>\n<p>The vast majority of best-of-five matches reach at least 80 service points per player, so the data for the 2nd and 3rd segments should be meaningful. \u00a0Beyond that, the sample size shrinks quickly, so there may be some bias for the 4th, 5th, and 6th segments.<\/p>\n<p><strong>Results<\/strong><\/p>\n<p>As you can see below, the results aren&#8217;t very clean, especially for the percentage of short points. \u00a0As always, it&#8217;s frustrating not to have more data&#8211;it would be fascinating to see whether some of the differences between these slams was similar to results on the same surfaces, or in similar weather conditions. \u00a0As it is, we can only draw the most basic of conclusions, and we can&#8217;t have a ton of confidence in those.<\/p>\n<pre>WIMBLEDON\n            Sample  AvgRally  AvgRally+  Short%\n1st 30         124      1.00       1.00    1.00\n2nd 30         124      1.03       1.01    1.04\n3rd 30         114      1.05       1.02    0.98\n4th 30          63      1.04       1.05    1.05\n5th 30          28      1.05       1.01    0.95\n6th 30           9      1.13       1.08    0.99  \n\nFRENCH\n            Sample  AvgRally  AvgRally+  Short%\n1st 30         196      1.00       1.00    1.00\n2nd 30         196      1.00       0.99    1.06\n3rd 30         171      1.20       0.94    1.00\n4th 30          92      1.20       0.95    1.08\n5th 30          37      1.03       0.95    1.02\n6th 30          13      1.02       1.00    1.14  \n\nAUSTRALIAN\n            Sample  AvgRally  AvgRally+  Short%\n1st 30         166      1.00       1.00    1.00\n2nd 30         166      0.98       0.98    1.10\n3rd 30         145      0.97       0.95    1.05\n4th 30          80      0.93       0.92    1.13\n5th 30          28      0.94       0.94    1.09\n6th 30           8      0.87       0.81    0.95<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>On Friday, some interesting ideas were batted around in the comments to my post on the 61-shot rally. \u00a0One of the simpler ones boils down to the question that titles today&#8217;s post: Do points get shorter as the match progresses? Two forces seem to work in opposite directions: As players get used to each other&#8217;s &hellip; <a href=\"https:\/\/www.tennisabstract.com\/blog\/2011\/08\/07\/do-points-get-shorter-as-the-match-progresses\/\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">Do Points Get Shorter as the Match Progresses?<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[96],"tags":[],"class_list":["post-425","post","type-post","status-publish","format-standard","hentry","category-research"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/posts\/425","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/comments?post=425"}],"version-history":[{"count":0,"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/posts\/425\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/media?parent=425"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/categories?post=425"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.tennisabstract.com\/blog\/wp-json\/wp\/v2\/tags?post=425"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}