PPG is meaningless, Giroux gets a lot of points on the PP, which really doesn't depend on Couts' play.
Have to break out aggregate stats to understand what's going on.
His ES play went way up when Couts finally got his legs back.
First 11 games: 2-4 6, last 6 games: 4-5 9
What is concerning is that after 1-4 5 in the first four games, Giroux is 0-2 2 in the last 11 games on the PP.
I doubt Giroux suddenly forgot how to play on the PP, so either it's bad luck or more likely, teams have scouted our PP, figured out our tendencies and learned to neutralize it, which explains why they've been moving personnel around and it has started looking better - but TK has to shoot from the right side, not do a Voracek imitation.
I can't get a xGF breakdown, but Giroux and Couts have horrible numbers this year, but I'll bet they started turning around the last half dozen games as well.