The definitions have blurred over the years with the advent of such amazing athleticism in the NBA. Size alone used to dictate position, not skill level. Not anymore. We'll see 7-footers grab a rebound and drain pull-up 3-pointers.

That would be Dirk Nowitzki, of course, the 7-foot power forward for the Mavericks. Seeing him as often as we have over the past six years or so is enough to consider how the position has evolved. We'll discuss the best power forwards over the years for their skills, ending with whom we believe to be the best.

But let's begin with a little history.

It really began with Bob Pettit, the rookie of the year in 1955 and star of the World Championship St. Louis Hawks of 1958 to Nowitzki, Kevin Garnett and Tim Duncan of today. Pettit was a raw-boned, tough 6-9, 215 pounds - equally capable of taking it to the rim or draining the 17-foot jumper. He wasn't a great athlete, but athletic enough to make every play in his day and finish his 11-year career averaging 26.4 points and 16.2 rebounds - and with 12,851 boards, he's still the all-time leading rebounder in Hawks history. Philadelphia's Dolph Schayes was a similar player to Pettit, although his talent didn't reach the same level.

But the position, which included superb defenders like Satch Sanders, changed dramatically from the likes of Pettit and Jerry Lucas as the 1960s gave way to the 1970s and players got bigger and stronger. There were always 'tweeners like Dave DeBusschere - just as there were always enforcers like Rudy LaRusso, Tom Meschery, Gus Johnson, Bill Bridges and Luke Jackson, and they gave way to the likes of Maurice Lucas.

They spawned the spectacular play of Spencer Haywood and Elvin Hayes, and the earliest standard of all-around skills in George McGinnis.

But the prototype progressed from mostly defensive orientation to scoring as we got to the 1980s. Buck Williams was a throwback of raw toughness and defensive orientation, but he could also score. And as the Boston Celtics regained prowess, Kevin McHale became the new archetype, with extraordinary low-post moves and touch, plus long arms and hands that made him an exceptional defender. Shortly thereafter was the arrival of the powerful Karl Malone. Blessed with great hands and defensive instincts, he developed a mid-range jumper that would make him the second-most prolific scorer in NBA history. Shawn Kemp and Derrick Coleman were about the same size as Malone with far better natural skills - arguably the most talented power forwards ever - but they never had the heads to go along with their gifts.

That brought a flurry of new faces - beginning with the most unlikely of the power forward superstars - the 6-4 3/4 Charles Barkley, who could dominate the game with rebounds, running the floor or scoring in so many ways. He initially weighed nearly 300 pounds but eventually molded down below 260 and was at his best. Along that same path came Chris Webber, always teasing us with amazing skills, but never quite reaching the lofty expectations of coaches, the media and teammates. The same goes for Rasheed Wallace.

Nonetheless, it was Barkley who ushered us in to the new breed of today, led by the group of amazing 7-footers - Duncan, Garnett and Nowitzki - and the best youngsters of today, Amare Stoudemire and Chris Bosh.

From all of that, we'll pick the best at each power forward skill set:

Best scorer: Karl Malone
Best rebounder: Charles Barkley
Best shooter: Dirk Nowitzki
Best passer: Chris Webber
Best athleticism: Shawn Kemp
Best low-post moves: Kevin McHale
Best defender: Buck Williams
Best ball-handler: Kevin Garnett

And that, of course, leaves us with Duncan as the best overall. He can do everything on both ends of the floor, including one of the most picturesque perimeter bank shots the NBA has ever seen. Granted, many people still refer to him as a center. But he came into the league as the forward to David Robinson on the Spurs. And from the time Robinson retired in 2003, Spurs coach Gregg Popovich has always put a less-skilled banger at center so Duncan could exhibit his exceptional ability away from the basket when needed.

And that's why we'll stick with Duncan and his four NBA championship rings as the standard for power forwards.