{"id":487,"date":"2011-09-26T05:00:04","date_gmt":"2011-09-26T11:00:04","guid":{"rendered":"http:\/\/67.227.157.91\/~kenpom\/wp_blog\/predicting-john-hensons-free-throw-percentage\/"},"modified":"2016-05-07T19:29:12","modified_gmt":"2016-05-08T01:29:12","slug":"predicting-john-hensons-free-throw-percentage","status":"publish","type":"post","link":"https:\/\/kenpom.com\/blog\/predicting-john-hensons-free-throw-percentage\/","title":{"rendered":"Predicting John Henson’s free throw percentage"},"content":{"rendered":"

Last season, North Carolina’s John Henson<\/a> made 47.9% of his 142 free throw attempts. What is a reasonable expectation for Henson\u2019s free throw percentage this season?<\/p>\n

One way to make a prediction is to look at players with a similar free throw percentage in a single season and see how they performed in the following season. Since 2005, there have been 24 players that have shot at least 120 free throws in a season, were within four percentage points of Henson\u2019s accuracy and took at least 100 free throws the following season.<\/p>\n

This is that group sorted by the player\u2019s free throw percentage in the following season:<\/p>\n

    Player            Yr1   Yr2 <\/u>\n08  Nick Murphy       51.3% 64.9%\n07  Thomas Sanders    50.0  63.4\n06  Will Thomas       51.6  62.2\n10  Olu Ashaolu       47.2  60.3\n05  Darius Glover     47.1  59.3\n09  Dinma Odiakosa    46.2  57.7\n05  Corey Rouse       50.0  57.3\n07  Shaun Pruitt      51.3  56.4\n07  John Fields       45.5  54.3\n07  Trent Plaisted    49.2  54.2\n06  Juwann James      45.9  54.1\n05  David Berghoefer  47.7  53.7\n06  Ryan Bright       44.7  53.6\n05  Joe Martin        51.3  53.1\n10  Damian Saunders   48.4  52.3\n10  Hamidu Rahman     51.5  51.8\n08  Marcus Lewis      45.5  50.3\n07  Jermaine Griffin  50.8  50.0\n05  Bruce Brown       45.6  46.0\n07  Lamar Sanders     51.3  44.7\n05  Dillion Sneed     48.0  38.7\n07  Joey Dorsey       46.7  37.8\n06  Durrell Vinson    48.1  32.5\n08  Arinze Onuaku     44.5  29.8\n    AVERAGE           48.3  51.6\n\n<\/pre>\n
As with many basketball skills, it is rare to show massive improvement from one season to the next in free throw shooting. Even though the average doesn\u2019t change much, there is a range of possibilities, from Jacksonville State\u2019s Nick Murphy<\/a>, whose 51% mark as a freshman rose to 65% as a sophomore and eventually 75% as a senior, to noted masonry aficionado Arinze Onuaku<\/a> who stretched the bounds of human performance by missing over 70% of his attempts as a junior. <\/p>\n
Based on this analysis, the future doesn\u2019t look all that bright. But as Carolina fans would be quick to point out were the investigation to end here, Henson might be a special case because he had a split personality at the free throw line, producing one of the most noteworthy mid-season improvements in college hoops last season*. And I suppose it\u2019s possible he had an epiphany sometime between February 16th and February 22nd. <\/p>\n
            FTM-FTA  Pct\nBefore 2\/22  39-101 .389\nAfter  2\/22  31-47  .660\n\n<\/pre>\n
The issue at hand is whether this is a statistical artifact or whether Henson did, in fact, consume some magic beans (or learn some kind of \u201csecret<\/a>\u201d) sometime during the third week in February. In order to get a handle on this, we need to know how well Henson\u2019s metamorphosis can be explained by chance. If Henson\u2019s true ability last season was to make 47.9% of his free throws, what are the chances he would luck into a stretch of making 31-of-47? <\/p>\n
In order to do this, I simulated John Henson\u2019s free throw shooting from last season a million times using my shooting simulation program, RandoShoot 3000TM<\/sup>. It\u2019s the same kind of cutting-edge technology that allowed us to guess at Derrick Williams\u2019 chance of breaking the all-time three-point accuracy record<\/a> late last season. I assumed that Henson had a 47.9% chance of making a free throw, and that he would shoot exactly 142 free throws in a season. For each of one million simulated seasons, RandoShoot 3000TM<\/sup> recorded Henson\u2019s best performance over any 47 consecutive free throws. The results follow.<\/p>\n
Most free throws made in any 47 consecutive attempts (with number of cases each was observed)<\/u><\/p>\n
14:      1\n15:      0\n16:      3\n17:     23\n18:    133\n19:    621\n20:   2398\n21:   7402\n22:  19380\n23:  41438\n24:  73907\n25: 110703\n26: 141340\n27: 153992\n28: 143412\n29: 116909\n30:  83329\n31:  51890\n32:  29173\n33:  14189\n34:   6217\n35:   2397\n36:    797\n37:    265\n38:     68\n39:     10\n40:      1\n41:      2\n\n<\/pre>\n
Even a 47.9% shooter would be expected to have a stretch as good as 27-of-47 (57.4%) at some point during the season. But he would only have about a 10% chance to have a run as good or better than Henson\u2019s closing 31-of-47. From a statistician\u2019s perspective, that\u2019s not exactly convincing evidence that Henson\u2019s finish was anything but random noise. Of course, the case in question is a bit more unusual since Henson\u2019s hot streak came at the very end of the season. <\/p>\n
One other way to attack this is to examine history, looking for shooters that finished the season shooting much better than they started and then checking how they shot in the following season. So I went back to the 2010 season for which I have nearly every play-by-play on file. I looked for players with similar splits to Henson. The rules I established were the following\u2026<\/p>\n
– Player must have shot at least 100 free throws in the 2010 and 2011 seasons. 
\n– A point in the season can be identified where the player shot at least 20% better after that point than before.
\n– The sample size after the identified point must cover at least 35 free throws but no more than half of a player\u2019s season total.<\/p>\n
The results are pretty amazing. The player with the biggest transformation in 2010 was Quinnipiac\u2019s Justin Rutty. He made exactly half of his first 88 attempts that season before closing the season on an astounding 51-of-63 (81.0%) run.  Clearly, any tests for significance would say \u201cthat\u2019s significant\u201d. You don\u2019t flip a coin 63 times and get heads 51 of those times without something being messed up with the coin. <\/p>\n
However, somehow Rutty fooled his own ability. In two prior seasons, he had posted season totals of 36.9% and 41.9%. The hot streak in his junior season lifted his FT% to 62.9. Given the closing performance in 2010, it would have been reasonable to assume that he would be closer to, or even better than, his season-long junior year performance as a senior. But in 114 attempts last season, he made just 44.7% of them. (Rutty did have bone chips in his non-shooting elbow which required surgery in the middle of his senior season, but he shot no better post-surgery.)<\/p>\n
Rutty\u2019s case is fascinating and actually, it\u2019s somewhat unusual. But the collective performance of the 15 players identified by my criteria indicates that a late and sudden improvement in free throw accuracy isn\u2019t as meaningful as you might think. Here\u2019s a list of all of the players that had a 20% jump in their FT% at some point late in 2010 and how their season-long FT% compared between 2010 and 2011.<\/p>\n
Player           Imp  2010  2011   Chg <\/u>\nJustin Rutty    .310  .629  .447  -.182\nHerb Pope       .271  .496  .548  +.052\nOrlando Johnson .257  .703  .804  +.101\nKendall Cutler  .247  .699  .686  -.013\nJake Cohen      .244  .709  .773  +.064\nBrian Conklin   .236  .643  .622  -.021\nKwadzo Ahelegbe .221  .739  .786  +.047\nHillary Haley   .220  .703  .729  +.026\nDevin Brown     .220  .773  .806  +.033\nJay Couisnard   .208  .718  .637  -.081\nCasper Ware     .207  .784  .810  +.026\nVerdell Jones   .205  .758  .672  -.086\nReggie Jackson  .204  .733  .796  +.063\nNoah Dahlman    .203  .702  .758  +.056\nShawn Lewis     .203  .727  .714  -.013\n                         AVERAGE  +.005\n<\/pre>\n
Imp = Improvement in FT% after epiphany point
\nChg = Difference in FT% between 2011 and 2010<\/p>\n
Some guys on the list improve and some guys don\u2019t, but in reality there\u2019s no evidence that a late hot streak has much more predictive value than a player\u2019s season-long FT%. Herb Pope is the most comparable player to Henson. The two have astonishingly similar splits. Pope closed on a 32-of-49 (65.3%) streak after starting 26-of-68 (38.2%) but he was just slightly better than his overall 2010 percentage last season.<\/p>\n
Henson will probably do better than last season, because as shown in the first table, guys who shoot as poorly as he did for a whole season tend to improve a little. It\u2019s simple regression to the mean. Or in regular-person\u2019s terms, there were a lot of things to fix in Henson\u2019s stroke and he\u2019s bound to fix some of that. The relative hot-streak to close last season may have partially been a result of that. (Still though, it could have just been noise.)<\/p>\n
A reasonable expectation for Henson\u2019s FT% is somewhere in the low 50s this season. You can\u2019t completely rule out that he\u2019ll sustain his late-season run in the mid-60s for an entire season, because there are cases of players improving like that. But that outcome is just as likely to occur as Henson channeling his inner Justin Rutty. <\/p>\n
*Henson\u2019s turnaround was the third-highest in D-I last season. East Tennessee State\u2019s Adam Sollazzo<\/a> started 83-of-138 (60.1%) before finishing a sizzling 37-of-39 (94.9%).<\/p>\n
(Update: Henson weighed in on twitter<\/a>. Hilarious.)<\/p>\n","protected":false},"excerpt":{"rendered":"
Last season, North Carolina’s John Henson made 47.9% of his 142 free throw attempts. What is a reasonable expectation for Henson\u2019s free throw percentage this season? One way to make a prediction is to look at players with a similar free throw percentage in a single season and see how they performed in the following […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[30],"tags":[],"_links":{"self":[{"href":"https:\/\/kenpom.com\/blog\/wp-json\/wp\/v2\/posts\/487"}],"collection":[{"href":"https:\/\/kenpom.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kenpom.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kenpom.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kenpom.com\/blog\/wp-json\/wp\/v2\/comments?post=487"}],"version-history":[{"count":1,"href":"https:\/\/kenpom.com\/blog\/wp-json\/wp\/v2\/posts\/487\/revisions"}],"predecessor-version":[{"id":1034,"href":"https:\/\/kenpom.com\/blog\/wp-json\/wp\/v2\/posts\/487\/revisions\/1034"}],"wp:attachment":[{"href":"https:\/\/kenpom.com\/blog\/wp-json\/wp\/v2\/media?parent=487"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kenpom.com\/blog\/wp-json\/wp\/v2\/categories?post=487"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kenpom.com\/blog\/wp-json\/wp\/v2\/tags?post=487"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}