Saturday, April 25, 2015

NFL Combine: Running backs edition

Its draft season in the NFL, and everyone here in less than a week will be gathered in Chicago to see the next crop of potential stars.  Two of the top players hoping to hear their names called on Thursday will be Melvin Gordon and Todd Gurley.  Both players dominated their competition throughout their collegiate careers.  However, this competition was different for each player, as were the offensive schemes they played in.  One of the most level tools draft evaluators have is the NFL combine.  The question most folks have though is how valuable is combine data for projecting future success.

In 2008 FootballOutsiders published their work on running back statistics and the NFL combine.  Their original findings indicated that a back's 40 time was the most likely indicator for success.  This lead to the development of their Speed Score Metric, which accounts for a player's size in relation to their 40 time.  Speed Score has had some success in unearthing later and mid round players, it only accounts for about 20% of the variability of running back statistics. 

I decided to re-run the correlations for all the players that have attended the combine from 2008-2013, see if there was any update.  What I ended up with is in the tables (in the read further section to keep this clean).  The comparison ran twice, once pairwise and once list wise.  Excluding options pairwise gives a result that I think is a little too limited, since may combine participants will not do every test, and that can skew some of the results (Players like Anthony Alridge, who was never going to be a running back in the traditional mold for example).  So, with a list wise exclusion we end up with some new results.  First, Speed Score continues to be a decent indicator for being able to identify potential large contributors in the draft.  Its correlation score of .3 was the highest amongst the other metrics for average rushing yards per season.  It also shared a .342 score for total offensive touches.  Pure 40 times were no longer as solid of an indicator of rushing yards, trailing the 3 cone drill and being in line with the broad jump (one an indicator of good agility, the other pure lower body power).  The three cone was also the second highest score for total offensive touches, with the 40 showing third there.

What does it all mean?  Basically the NFL combine is what most people think it is: not a great indicator of potential success.  But, it is pretty useful in identifying players that have the athletic ability to make it in the NFL.  Of the players that scored at least 100 on their speed score, 80% went on to have more than a single NFL touch.  Players that failed to had only 60% contribute at some point.






Descriptive Statistics
Stat Mean Std. Deviation N
Heightin 70.65 1.937 89
Weightlbs 214.69 11.634 89
@40Yard 4.5312 .11578 89
BenchPress 20.84 4.298 89
VertLeapin 35.079 2.6861 89
BroadJumpin 117.83 4.796 89
Shuttle 4.2598 .13894 89
@3Cone 6.9889 .18144 89
SpeedScore 102.4064 10.78140 89
RushingYardsPerSeasonAverage_B 232.48812198502 295.674009722309 89
RecievingYardsPerSeasonAverage_A 77.25650080225 113.150773874343 89
TotalYardsPerSeasonAverage 309.74462280075 387.529602327420 89
TotalTouches 256.26 383.624 89


Correlationsa
Exclude Pair Wise Heightin Weightlbs @40Yard BenchPress VertLeapin BroadJumpin Shuttle @3Cone SpeedScore RushingYardsPerSeasonAverage_B RecievingYardsPerSeasonAverage_A TotalYardsPerSeasonAverage TotalTouches
Heightin Pearson Correlation 1 .611** -.061 .004 .154 .080 .276** .068 .362** .119 .138 .131 .220*
Sig. (2-tailed)
.000 .568 .968 .150 .454 .009 .526 .000 .267 .199 .222 .039
Sum of Squares and Cross-products 330.202 1211.247 -1.212 3.124 70.438 65.775 6.543 2.105 664.417 5990.520 2653.882 8644.402 14362.011
Covariance 3.752 13.764 -.014 .035 .800 .747 .074 .024 7.550 68.074 30.158 98.232 163.205
Weightlbs Pearson Correlation .611** 1 .157 .297** .034 -.063 .374** .102 .356** .221* .083 .193 .181
Sig. (2-tailed) .000
.142 .005 .755 .555 .000 .339 .001 .038 .441 .071 .090
Sum of Squares and Cross-products 1211.247 11911.191 18.615 1305.596 92.202 -311.719 53.224 19.039 3934.028 66849.165 9581.308 76430.473 71060.236
Covariance 13.764 135.354 .212 14.836 1.048 -3.542 .605 .216 44.705 759.650 108.879 868.528 807.503
@40Yard Pearson Correlation -.061 .157 1 -.254* -.300** -.372** .249* .109 -.862** -.073 -.180 -.108 -.137
Sig. (2-tailed) .568 .142
.016 .004 .000 .019 .311 .000 .499 .092 .314 .200
Sum of Squares and Cross-products -1.212 18.615 1.180 -11.143 -8.209 -18.161 .353 .201 -94.710 -218.901 -207.323 -426.224 -536.318
Covariance -.014 .212 .013 -.127 -.093 -.206 .004 .002 -1.076 -2.488 -2.356 -4.843 -6.095
BenchPress Pearson Correlation .004 .297** -.254* 1 .108 .155 -.048 -.046 .390** .068 .136 .092 .085
Sig. (2-tailed) .968 .005 .016
.314 .146 .655 .670 .000 .525 .203 .392 .426
Sum of Squares and Cross-products 3.124 1305.596 -11.143 1625.798 109.601 281.640 -2.523 -3.146 1591.373 7639.136 5831.598 13470.734 12388.618
Covariance .035 14.836 -.127 18.475 1.245 3.200 -.029 -.036 18.084 86.808 66.268 153.077 140.780
VertLeapin Pearson Correlation .154 .034 -.300** .108 1 .492** -.302** -.153 .302** -.111 -.202 -.143 -.088
Sig. (2-tailed) .150 .755 .004 .314
.000 .004 .151 .004 .302 .058 .180 .413
Sum of Squares and Cross-products 70.438 92.202 -8.209 109.601 634.949 557.680 -9.928 -6.577 769.667 -7738.484 -5402.087 -13140.571 -7961.809
Covariance .800 1.048 -.093 1.245 7.215 6.337 -.113 -.075 8.746 -87.937 -61.387 -149.325 -90.475
BroadJumpin Pearson Correlation .080 -.063 -.372** .155 .492** 1 -.312** -.242* .310** .203 .113 .188 .147
Sig. (2-tailed) .454 .555 .000 .146 .000 &nbsp .003 .022 .003 .057 .290 .078 .169
Sum of Squares and Cross-products 65.775 -311.719 -18.161 281.640 557.680 2024.472 -18.303 -18.517 1408.565 25317.281 5416.776 30734.057 23814.876
Covariance .747 -3.542 -.206 3.200 6.337 23.005 -.208 -.210 16.006 287.696 61.554 349.251 270.624
Shuttle Pearson Correlation .276** .374** .249* -.048 -.302** -.312** 1 .544** -.046 -.048 -.156 -.082 -.009
Sig. (2-tailed) .009 .000 .019 .655 .004 .003
.000 .667 .654 .143 .443 .932
Sum of Squares and Cross-products 6.543 53.224 .353 -2.523 -9.928 -18.303 1.699 1.208 -6.086 -174.268 -216.291 -390.559 -42.905
Covariance .074 .605 .004 -.029 -.113 -.208 .019 .014 -.069 -1.980 -2.458 -4.438 -.488
@3Cone Pearson Correlation .068 .102 .109 -.046 -.153 -.242* .544** 1 -.037 -.197 -.283** -.233* -.228*
Sig. (2-tailed) .526 .339 .311 .670 .151 .022 .000
.730 .064 .007 .028 .031
Sum of Squares and Cross-products 2.105 19.039 .201 -3.146 -6.577 -18.517 1.208 2.897 -6.395 -930.746 -511.224 -1441.970 -1397.794
Covariance .024 .216 .002 -.036 -.075 -.210 .014 .033 -.073 -10.577 -5.809 -16.386 -15.884
SpeedScore Pearson Correlation .362** .356** -.862** .390** .302** .310** -.046 -.037 1 .174 .208 .194 .218*
Sig. (2-tailed) .000 .001 .000 .000 .004 .003 .667 .730
.102 .050 .069 .040
Sum of Squares and Cross-products 664.417 3934.028 -94.710 1591.373 769.667 1408.565 -6.086 -6.395 10228.988 48873.688 22358.352 71232.040 79333.037
Covariance 7.550 44.705 -1.076 18.084 8.746 16.006 -.069 -.073 116.239 555.383 254.072 809.455 901.512
RushingYardsPerSeasonAverage_B Pearson Correlation .119 .221* -.073 .068 -.111 .203 -.048 -.197 .174 1 .747** .981** .845**
Sig. (2-tailed) .267 .038 .499 .525 .302 .057 .654 .064 .102
.000 .000 .000
Sum of Squares and Cross-products 5990.520 66849.165 -218.901 7639.136 -7738.484 25317.281 -174.268 -930.746 48873.688 7693234.562 2197930.900 9891165.463 8432536.218
Covariance 68.074 759.650 -2.488 86.808 -87.937 287.696 -1.980 -10.577 555.383 87423.120 24976.487 112399.608 95824.275
RecievingYardsPerSeasonAverage_A Pearson Correlation .138 .083 -.180 .136 -.202 .113 -.156 -.283** .208 .747** 1 .862** .725**
Sig. (2-tailed) .199 .441 .092 .203 .058 .290 .143 .007 .050 .000
.000 .000
Sum of Squares and Cross-products 2653.882 9581.308 -207.323 5831.598 -5402.087 5416.776 -216.291 -511.224 22358.352 2197930.900 1126672.591 3324603.491 2769908.436
Covariance 30.158 108.879 -2.356 66.268 -61.387 61.554 -2.458 -5.809 254.072 24976.487 12803.098 37779.585 31476.232
TotalYardsPerSeasonAverage Pearson Correlation .131 .193 -.108 .092 -.143 .188 -.082 -.233* .194 .981** .862** 1 .856**
Sig. (2-tailed) .222 .071 .314 .392 .180 .078 .443 .028 .069 .000 .000
.000
Sum of Squares and Cross-products 8644.402 76430.473 -426.224 13470.734 -13140.571 30734.057 -390.559 -1441.970 71232.040 9891165.463 3324603.491 1.322E7 1.120E7
Covariance 98.232 868.528 -4.843 153.077 -149.325 349.251 -4.438 -16.386 809.455 112399.608 37779.585 150179.193 127300.507
TotalTouches Pearson Correlation .220* .181 -.137 .085 -.088 .147 -.009 -.228* .218* .845** .725** .856** 1
Sig. (2-tailed) .039 .090 .200 .426 .413 .169 .932 .031 .040 .000 .000 .000
Sum of Squares and Cross-products 14362.011 71060.236 -536.318 12388.618 -7961.809 23814.876 -42.905 -1397.794 79333.037 8432536.218 2769908.436 1.120E7 1.295E7
Covariance 163.205 807.503 -6.095 140.780 -90.475 270.624 -.488 -15.884 901.512 95824.275 31476.232 127300.507 147167.694
**. Correlation is significant at the 0.01 level (2-tailed).
*. Correlation is significant at the 0.05 level (2-tailed).
a. Listwise N=89







Descriptive Statistics

 Mean Std. Deviation N
Heightin 70.60 1.875 166
Weightlbs 212.28 13.298 166
@40Yard 4.5345 .11984 166
BenchPress 20.56 4.161 134
VertLeapin 34.456 2.9481 147
BroadJumpin 117.77 5.269 144
Shuttle 4.2676 .14784 109
@3Cone 6.9921 .17860 111
SpeedScore 100.9115 10.56159 166
RushingYardsPerSeasonAverage_B 213.42532988717 292.567598572645 166
RecievingYardsPerSeasonAverage_A 73.26616465815 108.747053754765 166
TotalYardsPerSeasonAverage 286.69149455819 385.148133913357 166
TotalTouches 260.10 412.800 166

Correlations
Excluded List Wise Heightin Weightlbs @40Yard BenchPress VertLeapin BroadJumpin Shuttle @3Cone SpeedScore RushingYardsPerSeasonAverage_B RecievingYardsPerSeasonAverage_A TotalYardsPerSeasonAverage TotalTouches
Heightin Pearson Correlation 1 .567** .046 .028 .111 .070 .237* -.002 .286** .142 .116 .141 .182*
Sig. (2-tailed)
.000 .557 .749 .180 .407 .013 .983 .000 .067 .136 .070 .019
Sum of Squares and Cross-products 579.958 2332.970 1.703 29.343 89.466 98.229 7.260 -.079 934.228 12885.504 3907.838 16793.342 23195.458
Covariance 3.515 14.139 .010 .221 .613 .687 .067 -.001 5.662 78.094 23.684 101.778 140.579
N 166 166 166 134 147 144 109 111 166 166 166 166 166
Weightlbs Pearson Correlation .567** 1 .297** .367** .045 -.100 .276** .083 .305** .186* .071 .162* .138
Sig. (2-tailed) .000
.000 .000 .592 .231 .004 .386 .000 .016 .362 .037 .076
Sum of Squares and Cross-products 2332.970 29179.693 78.028 2543.604 247.221 -969.937 52.223 19.999 7062.072 119627.559 16984.309 136611.869 124913.470
Covariance 14.139 176.847 .473 19.125 1.693 -6.783 .484 .182 42.800 725.016 102.935 827.951 757.051
N 166 166 166 134 147 144 109 111 166 166 166 166 166
@40Yard Pearson Correlation .046 .297** 1 -.181* -.323** -.468** .322** .117 -.815** -.183* -.185* -.191* -.249**
Sig. (2-tailed) .557 .000
.037 .000 .000 .001 .221 .000 .018 .017 .014 .001
Sum of Squares and Cross-products 1.703 78.028 2.370 -11.186 -16.889 -41.660 .596 .266 -170.209 -1057.872 -398.439 -1456.311 -2035.092
Covariance .010 .473 .014 -.084 -.116 -.291 .006 .002 -1.032 -6.411 -2.415 -8.826 -12.334
N 166 166 166 134 147 144 109 111 166 166 166 166 166
BenchPress Pearson Correlation .028 .367** -.181* 1 .053 .192* -.049 -.025 .388** .147 .159 .157 .173*
Sig. (2-tailed) .749 .000 .037

.036 .641 .807 .000 .090 .066 .069 .046
Sum of Squares and Cross-products 29.343 2543.604 -11.186 2303.022 73.483 475.067 -2.823 -1.832 2203.816 22766.987 8988.654 31755.641 36525.701
Covariance .221 19.125 -.084 17.316 .618 3.992 -.030 -.019 16.570 171.180 67.584 238.764 274.629
N 134 134 134 134 120 120 94 95 134 134 134 134 134
VertLeapin Pearson Correlation .111 .045 -.323** .053 1 .480** -.391** -.121 .335** .013 -.063 -.008 -.009
Sig. (2-tailed) .180 .592 .000 .563
.000 .000 .209 .000 .876 .452 .922 .916
Sum of Squares and Cross-products 89.466 247.221 -16.889 73.483 1268.963 1066.986 -17.436 -6.626 1574.647 1573.237 -2874.642 -1301.406 -1548.476
Covariance .613 1.693 -.116 .618 8.692 7.514 -.164 -.061 10.785 10.776 -19.689 -8.914 -10.606
N 147 147 147 120 147 143 107 109 147 147 147 147 147
BroadJumpin Pearson Correlation .070 -.100 -.468** .192* .480** 1 -.370** -.229* .382** .244** .168* .234** .225**
Sig. (2-tailed) .407 .231 .000 .036 .000
.000 .016 .000 .003 .044 .005 .007
Sum of Squares and Cross-products 98.229 -969.937 -41.660 475.067 1066.986 3969.437 -29.212 -23.060 3102.726 50144.475 13441.352 63585.827 64875.792
Covariance .687 -6.783 -.291 3.992 7.514 27.758 -.273 -.212 21.697 350.661 93.995 444.656 453.677
N 144 144 144 120 143 144 108 110 144 144 144 144 144
Shuttle Pearson Correlation .237* .276** .322** -.049 -.391** -.370** 1 .508** -.156 -.118 -.182 -.143 -.076
Sig. (2-tailed) .013 .004 .001 .641 .000 .000
.000 .106 .223 .058 .138 .430
Sum of Squares and Cross-products 7.260 52.223 .596 -2.823 -17.436 -29.212 2.361 1.383 -26.727 -545.576 -327.622 -873.198 -483.350
Covariance .067 .484 .006 -.030 -.164 -.273 .022 .013 -.247 -5.052 -3.034 -8.085 -4.475
N 109 109 109 94 107 108 109 106 109 109 109 109 109
@3Cone Pearson Correlation -.002 .083 .117 -.025 -.121 -.229* .508** 1 -.053 -.228* -.282** -.256** -.269**
Sig. (2-tailed) .983 .386 .221 .807 .209 .016 .000
.580 .016 .003 .007 .004
Sum of Squares and Cross-products -.079 19.999 .266 -1.832 -6.626 -23.060 1.383 3.509 -10.876 -1282.075 -620.632 -1902.707 -2030.897
Covariance -.001 .182 .002 -.019 -.061 -.212 .013 .032 -.099 -11.655 -5.642 -17.297 -18.463
N 111 111 111 95 109 110 106 111 111 111 111 111 111
SpeedScore Pearson Correlation .286** .305** -.815** .388** .335** .382** -.156 -.053 1 .300** .233** .294** .342**
Sig. (2-tailed) .000 .000 .000 .000 .000 .000 .106 .580
.000 .002 .000 .000
Sum of Squares and Cross-products 934.228 7062.072 -170.209 2203.816 1574.647 3102.726 -26.727 -10.876 18405.289 152809.097 44248.650 197057.746 245820.083
Covariance 5.662 42.800 -1.032 16.570 10.785 21.697 -.247 -.099 111.547 926.116 268.174 1194.289 1489.819
N 166 166 166 134 147 144 109 111 166 166 166 166 166
RushingYardsPerSeasonAverage_B Pearson Correlation .142 .186* -.183* .147 .013 .244** -.118 -.228* .300** 1 .800** .986** .857**
Sig. (2-tailed) .067 .016 .018 .090 .876 .003 .223 .016 .000
.000 .000 .000
Sum of Squares and Cross-products 12885.504 119627.559 -1057.872 22766.987 1573.237 50144.475 -545.576 -1282.075 152809.097 1.412E7 4200682.497 1.832E7 1.707E7
Covariance 78.094 725.016 -6.411 171.180 10.776 350.661 -5.052 -11.655 926.116 85595.800 25458.682 111054.482 103482.273
N 166 166 166 134 147 144 109 111 166 166 166 166 166
RecievingYardsPerSeasonAverage_A Pearson Correlation .116 .071 -.185* .159 -.063 .168* -.182 -.282** .233** .800** 1 .890** .735**
Sig. (2-tailed) .136 .362 .017 .066 .452 .044 .058 .003 .002 .000
.000 .000
Sum of Squares and Cross-products 3907.838 16984.309 -398.439 8988.654 -2874.642 13441.352 -327.622 -620.632 44248.650 4200682.497 1951277.081 6151959.578 5446347.279
Covariance 23.684 102.935 -2.415 67.584 -19.689 93.995 -3.034 -5.642 268.174 25458.682 11825.922 37284.604 33008.165
N 166 166 166 134 147 144 109 111 166 166 166 166 166
TotalYardsPerSeasonAverage Pearson Correlation .141 .162* -.191* .157 -.008 .234** -.143 -.256** .294** .986** .890** 1 .858**
Sig. (2-tailed) .070 .037 .014 .069 .922 .005 .138 .007 .000 .000 .000
.000
Sum of Squares and Cross-products 16793.342 136611.869 -1456.311 31755.641 -1301.406 63585.827 -873.198 -1902.707 197057.746 1.832E7 6151959.578 2.448E7 2.252E7
Covariance 101.778 827.951 -8.826 238.764 -8.914 444.656 -8.085 -17.297 1194.289 111054.482 37284.604 148339.085 136490.439
N 166 166 166 134 147 144 109 111 166 166 166 166 166
TotalTouches Pearson Correlation .182* .138 -.249** .173* -.009 .225** -.076 -.269** .342** .857** .735** .858** 1
Sig. (2-tailed) .019 .076 .001 .046 .916 .007 .430 .004 .000 .000 .000 .000
Sum of Squares and Cross-products 23195.458 124913.470 -2035.092 36525.701 -1548.476 64875.792 -483.350 -2030.897 245820.083 1.707E7 5446347.279 2.252E7 2.812E7
Covariance 140.579 757.051 -12.334 274.629 -10.606 453.677 -4.475 -18.463 1489.819 103482.273 33008.165 136490.439 170403.615
N 166 166 166 134 147 144 109 111 166 166 166 166 166
**. Correlation is significant at the 0.01 level (2-tailed).
*. Correlation is significant at the 0.05 level (2-tailed).




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