Try as they might, NFL teams cannot predict which draft prospects will turn into productive players. Teams do their homework and still draft players who fail miserably. It happens every year.
But with their owners' money and co-workers' careers at stake, smart personnel people can avoid falling into the same traps.
An evaluation of all 254 first-round picks since 2000 revealed the potential risks and rewards teams face heading into the draft this weekend.
Overall, 169 of the 254 first-round selections (66.5 percent) have met or exceeded expectations. Twenty-four percent exceeded expectations. One-third failed to measure up.
Receivers failed to meet expectations 52.4 percent of the time, surpassing quarterbacks (47.6 percent) for the highest rate of failure.
Based on the findings, teams holding the seventh through 10th overall choices should exercise extreme caution before drafting a receiver in those slots. Teams hoping to find quality defensive backs with the 21st through 32nd choices should also beware. And any team looking for a defensive end with the 16th through 20th choices might want to say a prayer first.
For while making wise use of first-round draft selections does not ensure success, repeatedly botching those choices essentially guarantees failure.
"That's where you can really get hammered," Carolina Panthers coach John Fox said. "Especially if it's a real early pick, because you're paying that guy like a future Hall of Famer and he hasn't played a down yet."
A look at what the past eight drafts can tell teams as they balance needs with value heading into the 2008 draft:
The safest positions
1. Interior offensive line
NFL teams drafted nine guards and centers in the first round since 2000. All nine met or exceeded expectations, making the interior offensive line the safest position in the first round.
Twenty of 23 first-round linebackers met or exceeded expectations, and it's far too early to write off the three stragglers. San Francisco's Manny Lawson, Pittsburgh's Lawrence Timmons and Dallas' Bobby Carpenter are young players with plenty of time to distinguish themselves.
3. Tight end
Eleven of 13 first-round tight ends met or exceeded expectations. Jerramy Stevens (2002, Seattle, 28th overall) and Anthony Becht (2000, New York Jets, 27th) fell short by Scouts Inc. standards, although Becht has started 106 regular-season games.
4. Defensive tackle, offensive tackle and running back.
Two-thirds of first-round picks at these positions met or exceeded expectations. Ten of 27 first-round defensive tackles exceeded expectations, as did eight of 24 first-round running backs and seven of 21 first-round offensive tackles.
The high-risk positions
Nineteen of the 37 chosen in the first round since 2000 failed to meet expectations.
"There's some teams that just are dead set against taking a receiver in the first round because history shows how many great ones are around in the second and third," said Billy Devaney, the vice president of player personnel for the St. Louis Rams.
Of the 21 quarterbacks drafted in the first round since 2000, only Pittsburgh's Ben Roethlisberger has exceeded expectations set by Scouts Inc. Half of the others have bombed or not yet justified their first-round pedigrees.
"If you are drafted in the first 10 picks and you are a quarterback, that means you're going to a team that's not real good, so they've got you in there for a reason," San Diego Chargers coach Norv Turner said. "That kind of starts the whole thing in motion the wrong way. The guy's getting beat up, thrown around, and it takes a strong guy to survive it."
Five trouble spots
1. Receivers taken seventh to 10th overall
Projecting talent at the position has long confounded NFL personnel evaluators, but teams holding the seventh through 10th overall choices should pay special notice to the risks.
Teams have drafted nine receivers in those slots since 2000. Seven of the nine -- Travis Taylor, David Terrell, Koren Robinson, Reggie Williams, Troy Williamson, Mike Williams and Ted Ginn Jr. -- have yet to measure up. All but Ginn have played long enough to realize their potential.
Of the nine, Burress and Roy Williams were the only ones to meet or exceed expectations set by Scouts Inc.
No other position, including quarterback, broke NFL hearts so frequently within such a specific slotting range since 2000.
2. Defensive backs taken 26th to 32nd overall
Five of the 10 failed to meet expectations. Only Oakland's Nnamdi Asomugha, drafted 31st overall in 2003, has exceeded expectations within that range since 2000. Disappointments included Jamar Fletcher, Mike Rumph, Andre Woolfolk, Derrick Gibson and Sammy Davis.
The 21st through 25th overall spots also produced five disappointments in NFL secondaries. Eleven defensive backs have been drafted in this range, with two becoming Pro Bowl players: cornerback Nate Clements and safety Ed Reed.
3. Defensive ends taken 16th to 20th overall
Four of the eight have failed to meet expectations. None has exceeded expectations. Bad luck might be to blame. Jarvis Moss, David Pollack and Kenechi Udeze experienced injuries or health issues early in their careers.
4. Quarterbacks taken among the top 10 overall
Ten of the 40 players drafted among the top five since 2000 have exceeded expectations. None was a quarterback. Four of the nine quarterbacks drafted that early have yet to meet expectations.
5. Receivers drafted 26th to 32nd
Four of the eight receivers drafted in this range have failed to meet expectations. Only one -- the Colts' Wayne -- exceeded them.
Five safe havens
1. Defensive backs drafted fifth overall and 11th through 15th
NFL teams drafted three defensive backs among the top five -- Sean Taylor, Terence Newman and Quentin Jammer -- and all three justified the investment. Each was the fifth player chosen in his draft class. Taylor was named to the most recent Pro Bowl posthumously.
Expectations were met or exceeded by all five defensive backs drafted 11th to 15th: Marcus Trufant, Darrelle Revis, Thomas Davis, Tye Hill and Deltha O'Neal. Trufant picked off seven passes last season. O'Neal disappointed in Denver, but he has two seasons with at least nine picks.
2. Linebackers drafted ninth to 12th overall
NFL teams found six linebackers in this range without making a bad choice. Brian Urlacher, Patrick Willis and Shawne Merriman exceeded expectations. Ernie Sims, Dan Morgan and Jonathan Vilma have played well enough to justify their draft status, Scouts Inc. determined.
3. Running backs drafted 19th to 25th overall
NFL teams found five running backs in this range, and all met or exceeded expectations: Steven Jackson, Deuce McAllister, Willis McGahee, Laurence Maroney and Shaun Alexander.
5. Guards and centers drafted in the second half of the round
NFL teams have drafted nine of them in the first round, all after the 16th pick, and none has disappointed.
Mike Sando covers the NFL for ESPN.com.