Since 2000, the Cowboys have drafted all five of their current need positions at a rate lower than that of the rest of the NFL. Perhaps that's why we're discussing those positions today.
Nonetheless, the 'Boys have managed to hit in a big way on some of their selections. Let's not forget defensive end Marcus Spears, outside linebackers DeMarcus Ware and Anthony Spencer, interior lineman Andre Gurode, and cornerbacks Terence Newman and Mike Jenkins were all drafted in the first or second round. The success of these players resulted in what has been a huge portion of the core of this team for the past five years.
But how do you define "success" in the NFL? Surely Ware and his 99.5 career sacks are an example of it. So is the outstanding run defense of Spencer and Spears, which is a bit more difficult to quantify.
One objective measure of NFL success is Pro Football Reference's Approximate Value. Approximate Value measures players' contributions to their teams via a number of statistics, and although it isn't necessarily useful for comparisons of players at different positions, the values can be quite handy when assessing the success of players within the same position.
Since 2000, the Cowboys' first and second-round safeties, defensive ends, outside linebackers, guards, and cornerbacks with the highest career Approximate Value scores are DeMarcus Ware (76), Roy Williams (58), Terence Newman (56) and Andre Gurode (52). Not a bad list.
Much of the Cowboys' drafting success has come in the latter portion of the 2000s, however, with the beginning of the millennium seeing picks like Dwayne Goodrich (Career AV of 1) and Tony Dixon (9) welcomed to Big D. It's really a tale of two half-decades, and the numbers bear it out.
Outside linebacker is the only position the Cowboys have drafted at a clip significantly superior to the rest of the NFL. Due in large part to Ware & Co., the Cowboys have ranked in the top 16 for sacks in the NFL in every season since 2007, including a league-leading 59 sacks in 2008.
Other than that, the cupboard has been pretty bare at the positions Dallas is currently targeting in 2012. Even with Roy Williams' relatively stout value (think the younger version), the 'Boys have managed to nab safeties with a combined AV of just 60.5% of the league average since 2000. They have also been behind the curve at cornerback and defensive end.
So is this evidence the 'Boys should target a pass-rusher, avoiding Alabama's Mark Barron at all costs? Not at all. With a relatively small sample size, it would be prudent for Dallas to take some league-wide trends into account.
Since 2000, the league as a whole has actually seen the greatest return on an investment among safeties and guards in the draft's early rounds.
You can see 69.4% and 58.9% of first- and second-round safeties and guards, respectively, have a career Approximate Value in the top quarter of all players at their position. In laymen's terms, that means safeties and guards are rarely "busts." Compare their numbers to the modest 41.6%, 39.8%, and 20.2% rates for defensive ends, outside linebackers, and cornerbacks, respectively.
On top of that, safeties and guards offer the most upside as well. You can see a whopping 18.3% of safeties drafted in the first two rounds since 2000 have been elite players, i.e. in the top 5% of all at their position. Meanwhile, cornerbacks in the same range jump to elite status just 4% of the time.
No matter how you slice it, it appears the safety and guard positions offer NFL teams the biggest bang for their buck, at least early in the draft. These statistics shouldn't be used as a standalone tool for draft decisions, but they can be a solid foundation from which the Cowboys might build their board.
For the 'Boys, that means safety Mark Barron and guard David DeCastro could be just what the doctor ordered on Thursday night.