The idea of a defensive performance index is simple: award points for certain defensive plays (tackles, sacks, interceptions, etc.), multiply a player's stats by those point awards, and total them up.

You can then rank the defensive players by total points, and for a different twist, you can divide their total points by the number of plays they were on the field to get a "points per play" statistic that truly measures a player's productivity.

I set out to do just this using the defensive statistics posted on hokiesportsinfo.com at the following address:

http://www.hokiesportsinfo.com/football/stats/teamcume.html

Statistics for plays from scrimmage and special teams plays were taken from the season-ending depth chart found on page 8 of the December 8, 2000 edition of "hokiesports.com the newspaper" (Vol, 18, No. 15).

Note that the calculations are for the regular season only and do not include the Gator Bowl. A Gator Bowl depth chart was not available, and Gator Bowl statistics also seem to have disappeared from Tech's web site.

First, a caveat: the defensive statistics posted on the hokiesportsinfo.com web site also include special teams plays and tackles, and that complicates things. I took the list of 41 players that are included in the "defensive stats" and eliminated all of the players who are not on the defensive two-deep roster. This got rid of the special-teamers like Wayne Ward who appear in the defensive statistics because they have made plays on special teams.

This knocked it down to 22 players, and then I deleted Benny Wolfe, who did not play more than 100 plays on defense and in fact played more on special teams than he did on defense (78 plays from scrimmage and 108 special teams plays).

I wound up with the following 21 players, all of whom played more than 100 plays on defense in the 2000 season:

DT: David Pugh, Chad Beasley, Kevin Lewis, Channing Reed, Dan Wilkinson
DE: Nathaniel Adibi, Jim Davis, Cols Colas, Lamar Cobb
LB: Jake Houseright, Ben Taylor, Philip Summers, Nick Sorensen, Brian Welch
CB: Eric Green, Billy Hardee, Larry Austin, Ronyell Whitaker
S: Cory Bird, Willie Pile, Kevin McCadam

Here are the points awarded for the defensive plays included in the statistics:

Notes:

1.) Tackles are complicated, and are calculated like this: when a player makes a tackle, he gets 1 point (assisted tackle) or 2 points (unassisted tackle). If it's a tackle for loss (TFL), he gets an additional 2 points, plus 0.2 points for every yard lost on the play. If the tackle for loss is a quarterback sack, it is calculated just like a TFL, but the player also gets 2 bonus points for the sack.

2.) Points for fumble return yardage are double what is awarded for interception return yardage because fumble recovery statistics typically include less return yardage than interceptions. Most fumbles are recovered on the ground, whereas most interceptions are made standing up with a chance to run. Fumble return yards should therefore be awarded points at a premium over INT return yards.

The fact that special teams plays are included in the defensive statistics provided on hokiesportsinfo.com complicates things and skews the results in many ways. For one thing, there are not as many "plays" available to a special teamer as there are to a scrimmage defender -- sacks, QB hurries, interceptions, etc. are not available in a special teams play, except for the rare instances where the opponent runs a trick play.

Not to mention that sometimes the special team plays are plays like kickoff returns or field goals, where making any type of defensive play is impossible.

So this means that a defender such as Philip Summers, who played about one-fifth of his plays on special teams, is going to have his point totals dragged down by those special teams plays. On special teams, he can't make a sack or an interception, so on average, he gets fewer points from his special teams plays, no matter how good a special teams player he is.

But on the other hand, the tackles Philip makes on special teams go into his point totals and help him out versus a player like defensive end Jim Davis, who didn't play a single down on special teams.

You can sum up the effect of playing on special teams thus:

1.) It increases a player's point totals by giving him more opportunities to make plays, most notably tackles.

2.) It decreases a player's "points per play" figure, because special teams plays don't provide as many opportunities to score points.

I tried to compensate for item number two by dividing the number of special teams plays in half when calculating the "points per play" statistic. So points per play = total points / (scrimmage plays + special teams plays/2). You can argue that I should have divided by a larger number or even thrown the special teams plays out completely, but it was hard to figure out exactly what to do, and that's the step I took.

And Now, the Results

So, given the point values outlined above, and the defensive statistics obtained from hokiesportsinfo.com, and the depth chart play totals from "hokiesport.com the newspaper" (geez, I hate that name), let's throw those 21 players and their stats into a spreadsheet and see what comes up.

Unfortunately, the table that shows each player's statistics and their resulting point totals is too lengthy and cumbersome to print here, but it can be viewed on the web at:

http://www.techsideline.com/tslextra/issue005/defensivestats.htm

The page at the above address lists the players from first to last in terms of total number of defensive "points" scored. If you would like access to my actual MS Excel spreadsheet instead of just a web page showing the stats, see the end of this article.

Without further ado, here are the total points scored by the players:

It's no surprise to see Ben Taylor and Cory Bird near the top of the list. Taylor is Tech's leading tackler and has taken more defensive snaps than any defender other than Ronyell Whitaker. Linebackers also have the opportunity to make every single play in the stat sheet: tackles, sacks, interceptions, it's all available to a linebacker.

Cory Bird's high point total and third place finish are a testament not only to his playing ability and team leadership, but to the versatility of the Rover (strong safety) position that he plays. Rovers get to do it all: rush the QB, defend passes, pick the ball off, provide run support, etc. The Rover really is a do-it-all position, unique among the non-linebackers in Tech's scheme. If you didn't realize how important a good Rover is in Virginia Tech's defense, I hope you do now.

Willie Pile in second place is a surprise. Willie made some nice plays this year, but I didn't realize that he made so many of them. But a quick look at Willie's stat line shows that he did it all: 56 tackles, 2 tackles for loss, 6 interceptions, 10 passes defensed, one fumble recovery, one forced fumble, and one touchdown.

Pile was one of only two defensive players to score a TD, which contributes a hefty 20 points to his total. He did it on an 11-yard interception return for TD against Akron, a play that netted him 31.1 of his 223 points (10 for the interception, 1.1 points for the 11 return yards, and 20 points for the TD).

Nathaniel Adibi is the other Tech player to score a touchdown, with a 36-yard fumble return for a TD against Central Florida. With 32.2 points on the play (5 for the fumble recovery, 7.2 for the 36 return yards, and 20 for the TD), Adibi wins the award for highest-scoring play of the year.

Side note: Cory Bird is shown on Tech's stat sheet as having a touchdown, but that was a special teams play, not a defensive play, so it was thrown out of my spreadsheet.

David Pugh being near the top makes sense. Pugh was all over the field and even tied for the team lead in sacks with 5. Defensive tackles do not get to roam around the field and make many plays, so the fact that Pugh finished fifth in total points from the DT position is phenomenal, especially when you consider that Pugh was tenth in terms of number of plays, but fifth in terms of points scored. Very impressive.

And in the all-important points-per-play category, which is the true measure of a defender's effectiveness on the field, here's how it shakes out:

According to the formula I've invented here, Willie Pile makes more plays during his time on the field than any other Virginia Tech defender. Again, at first glance this is a surprise, but as I noted above, Willie made every single defensive play there is to make this year, except for a QB sack or a QB hurry. If the free safety blitzed more in Tech's scheme, he would have those, too.

In second place is David Pugh. This numerical analysis fits what we all feel to be true from a subjective standpoint, namely that David Pugh is one hell of a football player.

Before the 2000 season, the Virginia Tech coaches remarked that in 1999, they felt that Pugh made more plays for his time on the field than Carl Bradley and Nathaniel Williams did, but they gave Bradley and Williams the starting jobs because they were seniors. I don't know if the coaches did any statistical analysis to come to their conclusion about Pugh, but I did, and I see now what they were talking about.

Pugh tied for the team lead in sacks (5) and QB hurries (10), and he even had an interception to boost his point totals.

Brian Welch is a surprise finisher at third in points per play, especially when you consider that one-fifth of his plays came on special teams. Brian scored points with high tackle totals during his time in the game, plus a sack and three QB hurries.

Right behind Welch is, of all people, Eric Green. Green was forced to play cornerback as a true freshman when injuries felled Larry Austin and Garnell Wilds, and he was eventually benched after the Miami game, so his high finish in points-per-play is a surprise.

Or maybe not. As a true freshman playing CB, Green was a lightning rod for opposing QB's and receivers. They threw at him a lot, giving him the opportunity to make plays. He had 31 tackles, including one for a loss of 22 yards, but what really boosted his point totals were his 4 interceptions (third on the team) and 12 passes defensed (first on the team).

This article is already huge, so I'll put up a few more tables without additional comments: total points sorted by position, and points per play sorted by position:

To download an MS Excel 97 spreadsheet containing all of the data and formulas that I have used here, go here:

http://www.techsideline.com/tslextra/issue005/defensivestats.xls

I hope the spreadsheet has no significant errors, and I hope you enjoyed yet another brain-bruising installment of "Inside the Numbers"!

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