I've been musing over this for a while.
First, let me acknowledge a couple things:
1. A 'skill' guy like Filppula isn't going to win a Selke unless he's amazing (see: Datsyuk, Pavel). Physically aggressive play is still a necessary component to what many in the media consider to be defense (this is also why the majority of Norris candidates/winners are also physically-oriented guys and why pure skill winners are rare; see Lidstrom, Nicklas).
2. There are people I'd take over Filppula regardless of the above point.
That said, I've wondered how much Selke attention Filppula would get if Datsyuk and Zetterberg were more offense-oriented players. He can PK well and is one of the safest players at ES in the league right now, in my opinion. Most other players in a 2C role that put up his offensive numbers are considerably inferior defensively. Unfortunately, he has an extremely non-assertive style that tends not to get him noticed as much.
I can't see him winning with his style of play nor the shutdown ability of some of the guys out there, but I could see him with a handful of top 5 finishes and a outside-to-decent chance of a top 3 finish or two. Am I alone in this observation?
Oddly enough, sometimes you have better offensive numbers than usual to win the Selke. Look at Draper when he won it in 2004 (?), he's only been good for at most 10-15 goals a year and that year he scored 20+ and had his best offensive production.
So while Datsyuk and Zetterberg are great defensively obviously, their offensive numbers help their cause.
I love Flipper, he's a great defensive forward, but is offensively too streaky or hot/cold or whatever.
It shouldn't matter as much, but some offensive production with the Selke does make a difference.
I firmly believe that a Selke is in Filppula's future. At the very least, a runner up.
I know you are a big fan of him, but this is a bit of a stretch.