Ernie Grunfeld knows what kind of impact a great center can have on a franchise, a city and a league. Currently the president of basketball operations for the Washington Wizards, Grunfeld was winding down his playing career with the New York Knicks in 1985 when the Knicks won the first NBA draft lottery, and with it the right to select Georgetown’s Patrick Ewing.

“Getting Patrick changed everything,” Grunfeld said.

His arrival ushered in an era of success that included 13 straight trips to the playoffs and two appearances in the Finals.

The Ewing example looms large as teams prepare for Thursday’s NBA Draft.

The team with the top pick, the Portland Trail Blazers, hasn’t publicly stated its intentions, but basketball history suggests that the franchise would be foolish to pass on Greg Oden, who has been compared to a young Ewing.

The 7-foot, 250-pound Oden played only one season at Ohio State, but his rare combination of size, strength, quickness and agility makes him potentially a once-in-a-generation player.

Though the nature of the position has changed in recent years from the traditional back-to-the-basket center in the mold of recent greats such as Ewing, Shaquille O’Neal and Hakeem Olajuwon to more multi-skilled big men such as Kevin Garnett, Dirk Nowitzki and Amare Stoudemire, teams that have won championships almost always have had a dominant post player.

San Antonio’s Tim Duncan – the first overall pick in the 1997 draft – recently captured his fourth title in nine seasons, and O’Neal won a championship in 2006 with the Miami Heat after winning three straight with the Los Angeles Lakers between 2000 and 2002.

Even as players such as Garnett and Nowitzki have redefined the way big men play and inspired a generation of 7-footers to play a more perimeter-oriented game, it’s worth noting that Duncan and O’Neal have accounted for eight of the last nine championships.

“When a guy like that comes along, you take him,” said Grunfeld, who nearly won a championship as general manager of the Knicks in 1994, when Olajuwon and the Houston Rockets beat Ewing and the Knicks in seven games in the NBA Finals. “If you get one of those guys, obviously you have a leg up. There are only two or three of them in the whole league.”

The issue is that fewer and fewer true centers exist despite the fact that the sport is drawing players from all over the globe. For every Duncan, O’Neal or Yao Ming – the top three post players in the NBA now – there are several players such as Garnett, Nowitzki, Stoudemire, Memphis Grizzlies forward Pau Gasol and Toronto Raptors 7-footer Andrea Bargnani, who was the top overall pick last June.

Still, passing on Oden would require serious courage for a franchise that is best remembered for taking center Sam Bowie over Michael Jordan in 1984, and despite the success experienced by nontraditional big men such as Garnett and Nowitzki over the years, their teams have not won championships.