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How Draft Round Affects a Defensive Back's and Linebacker's Career Performance

Zach FeinAnalyst IApril 25, 2009

SAN DIEGO - SEPTEMBER 07:  Linebacker Shawne Merriman #56 of the San Diego Chargers sets on the line of scrimmage against the Carolina Panthers on September 7, 2008 at Qualcomm Stadium in San Diego, California. The Panthers won 26-24.  (Photo by Stephen Dunn/Getty Images)

With the skill positions and linemen done and examined, there’s just two more positions left for me to look at: defensive backs and linebackers.

In the first four parts of this series, I’ve found that sixth round quarterbacks are nearly as good as third rounders, there’s a significant downward linear trend for a lineman’s performance based on draft round, there’s not much difference between a fourth round and seventh round running back, and there’s an obvious power trend between a wide receiver’s performance and draft round.

I’ve included at the end of this article a rundown of all positions combined into one analysis, with just the draft round as the variable.

Defensive Backs

Pro Bowls

The first graph shows the percentage of all defensive backs who made at least one Pro Bowl, at least two Pro Bowls, and at least three Pro Bowls in their career.



And this graph shows the career Pro Bowls attended by draft round.



There’s a clear pattern here. The drop from the first to second to third rounds is huge, and there’s no difference whatsoever between the fourth and seventh rounds—just like running backs. Let’s see if this is supported by any other data.

Interceptions

The graph below shows the number of career interceptions by draft round.



Similar the to two graphs above, there’s also little difference between the fourth and seventh rounds in terms of interceptions. The slope from the first to third rounds, however, isn’t as steep as the previous two.

So we know that the fourth round isn’t as good as expected. But is it because they have a lot of busts, or because they are lacking any superstars? The next graph shows the chances of having 20 or more career interceptions (or a good pick) and the chances of having five or less (a bad pick). I did not adjust those baseline numbers for each draft round.



What we see is that there’s a lacking of star players after the fourth round, but the number of busts rapidly increases every round.

Years Starting

The graph below, showing years as primary starter by draft round, brings up an interesting point.



Fourth rounders start over half a year more than seventh rounders, even though they don’t perform nearly as better as that would show. Why? Because teams are more likely to keep a higher-drafted player as a starter despite their early foibles than a seventh-rounder with the exact same stats.

The next graph is a twist on the second interceptions graph above. It shows the percentage of players who started at least five years or one-or-less years for his team.



You read it right: Every defensive back drafted after the second round has more than a 60 percent chance of starting just one year in the NFL. After the second round, there’s a less than a 20 percent chance that a defensive back will start for five or more years.

(Sample size note: Every round had above 88 defensive backs in the sample, with an average of 119.)


Linebackers

Pro Bowls

The graphs in this section will be the same as the ones above, except for the obvious difference in data.



A couple of observations: only three of the 94 drafted linebackers in the fourth round were ever selected to a Pro Bowl, and its three percentages are the lowest for any round save for the seventh.

The small space between the orange and red lines show that few linebackers are selected to just two Pro Bowls; 74 percent of those selected to two were elected to at least one more. Only wide receivers had a smaller gap (75 percent) of all the other positions I looked at.

The number of career Pro Bowls, as shown below, mirrors the graph above.



The drop from the first to the second round is substantial, a difference of 1.30 Pro Bowls. The first round had a total of 73 more Pro Bowls than the second round despite having 28 less drafted linebackers.

Both of these graphs show the third round ahead of and the fifth round right below (or above) the second. Let’s consult the other graphs to see if this is the case.

Sacks

Now, I know sacks is an inexact measurement for linebackers, but tackles never became an official stat until this century, and past numbers are nowhere to be found.



Aside from the increase from the fourth to the fifth round, there’s a decline in sacks from each round to the next. When it comes to career stats, the fifth round falls short of both the second and third rounds.

The graph below shows the percentage of linebackers with 20 or more career sacks and five or less career sacks.



The difference between the stars in the third, fourth, and fifth rounds is next to nothing. But the number of busts steadily increases every round except for the fifth round. Still, over 60 percent of third round linebackers have five or less career sacks.

Years Starting

Will teams fall prey to the high-pick-means-high-playing-time theory again?



The graphs above show that the fifth round is better than the fourth and that the third is better (or just equal to) the second round. But teams again stick with their early picks for longer than they should and don’t start lower picks as long as they should.

(Sample size note: Every round had at least 62 linebackers, with an average of 86.)


A Review of All Positions

Pro Bowls

The following graphs show the effects of draft round on a player regardless of position. This first graph shows the chances of being selected to one, two, or three Pro Bowls.



We see a steep decline after round one and an increase from the fourth to the fifth round. When we look at career Pro Bowls, will we see the same?



In this graph, we see a drop of almost 0.80 Pro Bowls from the first round to the second round. The difference of just 0.06 Pro Bowls from the fourth to the seventh round again suggests that there’s not much variation in the latter rounds. From what we’ve seen so far, it would be wise for teams with multiple fourth round picks (such as San Diego, with three) to trade up in the draft for a second or third round pick.

Years Starting and Fantasy Points

But the way the NFL trade value charts are set up suggests that there’s a logarithmic or exponential curve to the value of each pick or round. The next three graphs back this up.



The correlation between draft round and years started is almost perfect—0.998. The formula 6.88 x 0.72 ^draft round produces a near-perfect estimate of years as a starter.

The graph below shows the chances of starting five or more years or one or less years by draft round. Again, the line showing five or more years follows an exponential trend as well, and the line showing busts is nearly linear.



There’s just one more stat to look at: fantasy points. I found the number of fantasy points (with half a point per reception) for quarterbacks, running backs, and wide receivers only—tight ends were excluded because some are drafted solely for blocking—and then found the average career total for each of them.



Although there’s still the obvious exponential trend, the slope isn’t nearly as steep as the NFL draft pick value chart created by Jimmy Johnson. I took the median value in each round as graphed it with career fantasy points; you can see the resulting graph here.

Both value the first round equally, but the chart has every remaining round significantly lower than the career fantasy points. Luckily, however, there’s an almost even relationship between career Pro Bowls and pick value, with the exception of the fifth round.


What Does All of This Mean?

1. When it comes to defensive backs, there’s a big drop from the first to the third rounds, but there’s no huge difference between the fourth round and the seventh round.

2. Fifth rounders perform better than fourth rounders—and nearly as good as third rounders—but they start quite less than both of them, because they have less chance to shine due to their draft round.

3. It turns out that draft round does in fact affect the career performance of every player. There’s a clear correlation between draft round and Pro Bowls, years starting, and fantasy points. The latter two do not have as large as a downward slope as the draft pick value chart, but the graph of Pro Bowls versus pick value is very similar.

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