Jon Gruden did the unconventional last season. Despite having the league's 27th best running attack, Gruden's Tampa Bay Buccaneers won the Super Bowl.

In a sport grounded in the tradition of needing a great running attack, Gruden disguised his backfield inadequacies in a smart, accurate passing attack and generated enough offense to be a winner. Of course, disciples of the West Coast offense have been playing that game for more than two decades, ever since Bill Walsh brought the West Coast offense into play in San Francisco.

	Mike Alstott could enter the season as the Bucs lead back

Still, the uncertainty of Michael Pittman's future because of pending domestic assault charges makes one wonder if the Bucs can repeat as Super Bowl champs without him. Mike Alstott is a powerful inside runner who's too one-dimensional to maintain a successful ground attack for 16 games. Backup Aaron Stecker is an unknown. Replacement options aren't around unless the Bucs acquire Thomas Jones, Pittman's former Cardinal teammate who wasn't good enough to beat him out.

The question facing the Bucs and a few other Super Bowl contenders is just how much of a running threat is needed to win a championship.

"You've got to be at least good enough running the ball to be in the top 15," Ravens general manager Ozzie Newsome said. "You still need to be able to effectively run the ball. You don't have to be No. 1 in the league. But you've got to be good enough with your running game to keep the other team's offense off the field, particularly in the fourth quarter if you have the lead."

That's why the Bucs are in trouble if Pittman is unavailable this season. Though Pittman rushed for only 718 yards and averaged 3.5 yards a carry, he caught 59 passes for 477 yards. Plus, Alstott could move over to halfback in the fourth quarter and wear down defenses when the Bucs had the lead.

The game has changed in the sense that offensive balance is no longer 50-50 in comparing the run versus the pass. Balance is now 60-40 in favor of the pass, but teams are in trouble if they throw the ball more than 60 percent of the time.

Without Pittman, though, Gruden may have a tough time manufacturing 400 respectable running plays next season. Unlike a lot of teams, the Bucs can't make running yards with their quarterback. Brad Johnson is a pocket passer with limited mobility. Alstott hits the hole so hard that his big body would wear down after 200 carries.

His career high is 242 carries, and he's only had more than 200 carries twice. Plus, he turns 30 this December. If Pittman isn't available, Gruden may have to sleep overnight at the office to find ways to manufacture the other 200 carries.

But Gruden won't be alone. There is an interesting transition going on in the NFL regarding running backs. The best backs are aging and there may not be equal replacements for all the great ones leaving the game in years ahead.

Seventeen of the league's current starters are 28. Although year-round conditioning has allowed more backs to be successful in their early 30s, age 30 is a scary one for running backs. That's the time when many lose the ability to turn those seven-yard runs into 15- to 20-yard gains. Those 4.3-yard per carry averages start turning into 3.7-yard totals.

Emmitt Smith (34), Garrison Hearst (32), Jerome Bettis (31), Charlie Garner (31), Antowain Smith (31), James Stewart (31), Curtis Martin (30) and Marshall Faulk (30) are all Pro Bowl backs -- most of which are in the declining stages of their careers. Before the end of the year, Priest Holmes and Eddie George will be celebrating their 30th birthdays.

Who knows if anyone will emerge from this year's horrible draft class of running backs to replace these players in years ahead. Though some may end up starting, it's doubtful that many will maintain the level of consistency established by the outgoing group.

The league may be entering an era in which more coaches will do what Gruden might be faced with this season. Since 1993, there have been 155 1,000-yard rushers, and the only new consistent 1,000-yard runners are Ricky Williams, Shaun Alexander, Ahman Green, Jamal Lewis and LaDainian Tomlinson. Deuce McAllister, Travis Henry, William Green, Clinton Portis and Michael Bennett are the next wave of runners.

But that isn't enough volume to replace the 57 1,000-yard seasons of Smith, Martin, Bettis, Faulk, George, Hearst, Corey Dillon, Terrell Davis, and Stephen Davis.

		The good news for the Bucs is that times have changed and running attacks don't have to be great. They just need to be good. The bad news is that the Bucs were barely acceptable last year on the ground and losing Pittman would be devastating.

What the Dolphins learned last year is having the best back doesn't mean winning a championship or even making the playoffs. Williams led the league with 1,853 yards, but the Dolphins missed the postseason because of a tie-breaker. In fact, four of the top five rushing teams -- Minnesota, Miami, Kansas City and Denver -- didn't make the playoffs.

It's a different era, but the running game is still important. The Patriots resurrected the career of Antowain Smith and he rushed for 1,157 yards in 2001. Though the running game ranked 13th, the Patriots got enough out of the running game to win a Super Bowl.

Andy Reid of the Eagles prefers to throw more screen passes than call for straight handoffs, but he's been able to manufacture enough of a running threat with Duce Staley to go to back-to-back NFC title games. Mix in Staley with the stable of young runners on the Eagles roster, and Reid can maintain the proper 60-40 pass-to-run ratio and have enough to wear down a defense with a fourth-quarter lead.

Pittman's legal issues may linger throughout the summer, which puts the Bucs in trouble. Their current configurations of runners won't meet the minimum standard of even last year. A year ago, the Bucs rushed for 1,557 yards. Pittman had 718. Alstott had 548. Stecker came off the bench for 174. It was enough.

Had they signed Emmitt Smith, they would have been fine, but the Bucs couldn't offer more than the minimum salary because of the cap. What the Bucs can't afford to do is let Jones slip away. The danger of not trading for him is that if he is cut by the Cardinals, he'll probably be claimed by the Bengals.

The good news for the Bucs is that times have changed and running attacks don't have to be great. They just need to be good. The bad news is that the Bucs were barely acceptable last year on the ground and losing Pittman would be devastating.

Another interesting team to watch will be the Cowboys. What if Troy Hambrick isn't the answer? Does Bill Parcells have enough options other than Michael Wiley to get to the middle of the league in the rushing stats.

It took 3½ years for the Browns to get a runner to get their offense going with Tim Couch in control. William Green came on during the second half of the season and the Browns made the playoffs. David Carr is undergoing a similar transition waiting for his featured back in Houston.

It's getting harder to find quality backs. The Bucs have to hope they won't have to find another one.

John Clayton is a senior writer for ESPN.com.