With minicamps now over, NFL coaching staffs finally get to take a vacation until the end of July. But there’s no break for fervent fans, because the fantasy football season is just beginning.

As dozens of fantasy magazines hit newsstands, it’s worth taking a look at the all-important and highly unpredictable question of who the league’s top running backs will be in 2005.Nearly every forecaster expects this year’s top-10 list to be a mix of the top names from 2003 and 2004, but there is substantial turnover on the list of the NFL’s top rushers nearly every season. Only once in the past seven seasons have more than five running backs made the top 10 in rushing yards for two straight years. During the period from 1999-2004, only seven backs appeared in the top 10 for three consecutive seasons, and only three of those backs – Marshall Faulk, Clinton Portis, and LaDainian Tomlinson – appeared in the top eight for three consecutive seasons. This year, a phalanx of promising youngsters means that turnover is even more likely.

Why so much change? Significant injuries are common at all NFL positions, but running backs are more likely to be injured the more they carry the ball. And of course, the players with the most carries usually gain the most yards. The effect builds up over multiple seasons, which is why running backs peak earlier than other players – usually around age 28 – and stay at their peak for a shorter period of time.

New names among the NFL’s top running backs are generally younger players on the rise. But last year was a significant exception. When the top five running backs of 2003 all fell out of the 2004 top five, it was a group of experienced backs that replaced them. In the past 20 years, only six players have established a career high with at least 1,250 rushing yards at age 29 or older, and half of these seasons came last year: Curtis Martin of the Jets, Tiki Barber of the Giants, and Corey Dillon of the Patriots.

All three are now in their thirties, as is another running back whom many are projecting among this year’s league leaders, Priest Holmes of Kansas City. But only 19 times since 1978 has a running back in his thirties appeared among the NFL’s top 10 rushers.

These trends need not worry Giants fans, as Barber just turned 30, and his 2004 total of 322 carries was a reasonable eighth in the NFL. But Jets fans beware: Martin, more than any other runner, is poised for a fall. He didn’t just break records in yards and carries for a running back over age 30 last season, he shattered them. Martin’s 371 carries at age 31 could easily cause nagging injuries that would trouble him all season. With that in mind, the Jets made their best move of the current off-season when they signed free agent Derrick Blaylock to be an experienced (but still young) backup as an insurance policy for their aging star.

When the leading rushers of 2004 decline, the leading rushers of 2003 are not likely to return to prominence. Baltimore’s Jamal Lewis was overused with 387 carries that season, and has battled injuries since, while Ahman Green watched Green Bay’s two best offensive linemen ditch him in free agency.

Who will replace these veterans in the NFL’s rushing elite? According to projections from my forthcoming book, “Pro Football Prospectus 2005,” four young running backs should finish among this year’s top 10 runners and take their place as the NFL newest elite class of runners:

* Domanick Davis, Houston: Davis emerged as the Texans’ starter midway through his 2003 rookie sea son, but last year he spent the first two months struggling with a sprained ankle and then a bruised thigh. In Weeks 1-8, he averaged just 2.9 yards per carry and scored only three touchdowns. But in the last nine weeks of the year, finally healthy, he improved to 4.5 yards per carry, 99 yards per game, and scored 10 touchdowns. The Texans play in a division where the Titans and Colts struggle to stop the run, and they get to play the weak NFC West as well, so Davis should explode out of the gate.

* Julius Jones, Dallas: Last year, coach Bill Parcells held Jones out of the lineup for the first half of the season so the rookie could work on picking up blitzes and learning the intricacies of the NFL game. Upon entering the starting lineup in Week 11, he was a workhorse, averaging 115 yards and a touchdown per game with at least 20 carries in all seven of his starts and at least 80 yards in six of them. Improvements to the Dallas defense should lead to more situations in which Parcells repeatedly hands the ball to Jones late, to grind time off the clock.

* Kevin Jones, Detroit: Jones is another young running back who was significantly hobbled by injury in the first half of 2004 (a high-ankle sprain kept him to just six carries during a four-week period from mid-September to mid-October). Once healthy, he blossomed. Of his 1,133 total yards, 911 came in the final eight weeks, an average of 114 per game. Jones overcame mediocre Detroit blocking by maximizing every opportunity he had in the open field – no other running back gained a higher percentage of his yards on double-digit runs – so any small improvement in Detroit’s offensive line this season will have a magnified effect on Jones’s numbers. A passing game featuring Detroit’s last three first-round draft picks in the receiver slots will also keep defenses from stacking the line against Jones.

* Willis McGahee, Buffalo: McGahee is the one young back who is being touted by most prognosticators as one of this season’s top runners. He averaged 88 yards per game last year after taking over as Buffalo’s starter in Week 6, and he should improve now that his infamous 2003 Fiesta Bowl knee injury is a year further in the past. But the Buffalo line must overcome the loss of left tackle Jonas Jennings, who signed with San Francisco in free agency. Last year, McGahee averaged 6.0 yards on runs behind left end or left tackle, but just 3.8 yards on all other runs.

These four young running backs are stocked with talent and will be given every opportunity to succeed. But several other young backs have the talent to perform just as well if circumstances change slightly. Second-year back Steven Jackson averaged 5.0 yards per carry for the Rams last year and would be projected to finish among this year’s top-10 rushers, except that the Rams still plan on giving veteran Marshall Faulk significant carries to keep Jackson fresh. Denver’s Tatum Bell averaged 5.3 yards per carry in 2004, but he will lose carries to other members of the crowded Broncos backfield. Miami rookie Ronnie Brown finished 11th in my rushing projections – until it became clear that Ricky Williams would return and share the load for the Dolphins.

Mr. Schatz is the editor in chief of FootballOutsiders.com. His full projections for the 2005 season will be published in “Pro Football Prospectus 2005,” available in August.