At the expense of a top-pair guy? Again, Pitkanen does not and has not played with a top pairing assignment. You're letting TTOI blind to this reality. He virtually never went out against the top line, at least not intentionally. It's more about effectiveness than it is about style.
I'm not sure how you're defining a "top pairing assignment" here.
Last seasons
even strength TOI averages looked like this:
Faulk - 18:22
Pitkanen - 17:54 *
this becomes a team-leading 19:00 if you subtract the games where he was injured early
Harrison - 17:16
Gleason - 16:39
McBain - 16:18
Corvo - 15:46
Sanguinetti - 13:00
Clearly he was skating first-pair
minutes, regardless of his matchups.
Then you look at QualComp:
Faulk - .897
Gleason - .850
Pitkanen - .813
Harrison - .646
McBain - .271
Corvo - .149
Sanguinetti - -.362
And most-common pairings:
Pitkanen - McBain/Sangs
Faulk/Corvo - Gleason
Harrison - Rookie/Corvo
Taken together, while it's clear that the shut-down pair of Faulk and Gleason absorbed the toughest assignments (which is what you would expect given their role), that doesn't translate into sheltered minutes for Pitkanen. It simply means he was being used in a more offensive role, babysitting a one-way partner, and given large minutes at ES with a higher percentage of his time spent in the offensive zone.
Strictly speaking, I guess you could say Pitkanen wasn't on the "top pairing" in the sense that we didn't exactly
have a top pairing. We had one guy (Pitkanen) who skated a ton of minutes at ES at both ends of the ice, a shutdown pairing, and a rotating cast of infill characters who had to be sheltered in one way or another. But generally speaking, a guy who skates the most minutes at ES and PP, and also takes a regular PK shift and isn't sheltered in any significant way, would be considered your #1 defenseman.