I've always been both enamoured and frustrated with Sergei Fedorov. I've always been wowed by the intelligence and beauty of his game, though he remains more enigmatic than ever. I can't decide if he's so subtly brilliant that he's actually terribly under-rated, or, as Brett Hull suggests, if he's so unaware of how good he could be that he doesn't give that extra effort and therefore underachieves and is terribly over-rated.
With Sergei Fedorov's recent switch to the blueline, I've had a close interest in his game. I've often felt if there was one star of this era who could make the move to defense, Feds would be the guy. He's got good size, good skating, excellent puck skills and the intelligence to make an impact. I also believe he'd be more challenged at this position, perhaps motivating him beyond the enigma title. And by most accounts he has fared quite well so far.
Now swing players are nothing new. However often it is poor skating physical defenseman moved up on the wing to give a 4th line physical presence and/or a 7th defenseman in case of injuries. Wade Belak, Christoph Schubert, and John Erskine are current examples. The best transition has to be that of Red Kelly in the 1960s, with acknowledgement to Lindy Ruff in Buffalo the 1980s and Jimmy Roberts in Montreal in the 1970s. But the norm is unimaginative, aggressive players.
It is pretty rare to see forwards dropped back on defense though, except to quarterback a power play. Learning NHL defense is a life long process, so to make the sudden switch back requires a tremendous understanding of the game. When you're a defenseman you're outlook is different. More often than not the game is coming right at you, which is rare as a forward. It is more reactionary than creative.
Fedorov is the most recent, though he's done it in the past with Detroit. Philadelphia used Sami Kapanen on D at times, and he did quite well as well despite his size. But both have been temporary. Eric Dandenault and Marty McSorley are two recent and permanent successes.
The best modern day example would have to be Mark Howe. He was a superstar forward, mostly in the World Hockey Association. In fact, an argument could be made he was the best player period in the WHA. He also played on the blue line at times, and made the permanent switch in the NHL with the Philadelphia Flyers. With a style very much like Fedorov at his best, Howe was unfortunate not to win a Norris Trophy.
The game was quite different pre-WWII, but the transition is no less impressive. There were three notable players to make the switch:
Detroit's Ebbie Goodfellow and Montreal's Babe Siebert both won Hart Trophies and Stanley Cups after anchoring the back end. And Boston's Dit Clapper is the only player in National Hockey League history to be named as an All Star both at forward and on defense.