It's an exercise I've engaged in myself, but it misses the main point. Even if you take the 50-50 measure as gospel, how does that compare to draft choices at other positions?
To answer that question, I looked at all of the first round draft choices from 1979-2003 -- a twenty-five year period that excludes guys who are too young to pass judgment on, and here's what I found.
1) The overall success rate for first round picks is 59 percent. That's how many of the players drafted went on to spend at least five season as a starter. Thirty-seven percent of the first-round picks went to at least one Pro Bowl.
2) Running backs are the riskiest pick, but they're boom or bust. Only 41% of them taken in the first round spend five seasons as a starter -- the lowest for any position. However, the highest percentage of them go on to become Pro Bowl players.
3) Quarterbacks are boom or bust, too. Fifty percent don't make it, but you've got a better chance of getting a superstar at quarterback than any other position. Forty percent go on to become Pro Bowl players. What's more, eight percent of QBs taken in the first round go on to the Hall of Fame, and that number's deflated when you consider that there were at least three HOF-caliber QBs active last year (Favre, Manning, Brady).
4) Teams use more picks on defensive linemen than any other position. Over the 25 year period, they accounted for 21.3% of all first round picks -- even though they only account for 3 or 4 of the 22 starting positions. The success rate for them (62% 5-year starters, 32% Pro bowlers) isn't much better than average, suggesting that teams make more reaches at these positions than any other.
5) Teams use fewer picks on offensive linemen, even though they are by far the safest pick. Seventy percent of them become five-years starters, by far the highest total for any position. It's 72% for guards, 70% for centers, and 69% for tackles. Only 17% of first round picks are used on offensive linemen, even though they account for almost a quarter of the starters.
6) Defensive tackles are also overlooked. Seventy percent become starters, and 43 percent of the DTs taken in the first round end up going to at least one Pro Bowl.
7) Kickers and punters shouldn't go in the first round. Two teams have used a first round pick on them in the past 25 years. The Raiders selected kicker Sebastian Janikowski in 2000, and the Saints tabbed punter Russell Erxleben in 1979. Neither guy ever went to a Pro Bowl, which seems like the bare minimum you can ask for a kicker taken in the first round. (I hate to play the "who else could they have picked" game, but Erxleben went two spots ahead of Hall of Fame tight end Kellen Winslow, and Janikowski went two spots ahead of RB Shaun Alexander.)
Here's the raw data:
Percentage by Position Total
ProBowl 5+ St HOF Picks
OL 37.9 70.2 3.2 124
LB 38.8 66.3 2.5 80
TE 39.1 65.2 4.3 23
DL 31.8 62.3 1.3 154
DB 38.9 61.1 2.8 108
WR 35.0 52.5 2.5 80
QB 40.0 50.0 8.0 50
RB 41.6 40.6 3.0 101
K/P 0.0 0.0 0.0 2
Tot 37.2 59.0 2.9 722
I think it's important to point out that this is not predictive data... it doesn't mean that every team should take an offensive linemen, because there are never going to be 32 linemen worthy of being drafted in the first round. This is historical data that should serve to provide some parameters for what constitutes success. Thirty percent of O-Linemen are busts, fifty percent of quarterbacks, and sixty percent of running backs. Let the buyer beware.