For reference, the Selke winners since the '05 lockout:
Year Name Age Team G A Pts
2012-13 NHL Jonathan Toews 24 CHI C 23 25 48
2011-12 NHL Patrice Bergeron 26 BOS C 22 42 64
2010-11 NHL Ryan Kesler 26 VAN C 41 32 73
2009-10 NHL Pavel Datsyuk 31 DET C 27 43 70
2008-09 NHL Pavel Datsyuk 30 DET C 32 65 97
2007-08 NHL Pavel Datsyuk 29 DET C 31 66 97
2006-07 NHL Rod Brind'Amour 36 CAR C 26 56 82
2005-06 NHL Rod Brind'Amour 35 CAR C 31 39 70
We know from last season and from brief moments this season that Stepan definitely has the defensive game for the trophy. IMO last season Stepan's defensive game was elite. He has been too inconsistent this season to indicate whether or not he can sustain that level of high play. I'm beginning to question if his lack of consistency is in part due to the new defensive system deployed by Vigneault.
His offensive game is going to be the biggest hurdle. He would probably need to score more than 60 points to get serious consideration. He's still young and put up over 50 two seasons ago. We saw last season that he was capable of putting up more (even though the sample size is a little too small for my liking). Just like his defensive game, it is all going to come down to consistency. He's not superbly skilled in any facet of his offensive games and relies on his "smarts". Players of his type often start out inconsistent, and either stay in this mindset or eventually develop the mental fortitude to deliver results continually.
As others have mentioned, he will need to become a "big name player" which will only come with time. Toews has been the youngest player to win since the '05 lockout and he was only 24. However, someone with his kind of accomplishments in the playoffs most certainly garners attention more quickly than a player with Stepan who has not been as far in the playoffs and is on a mediocre roster.
With all of that said, a Selke is definitely a realistic possibility within the next four or five years. The sooner he finds some consistency the sooner he will become a serious contender for the award.