Coincidently his 'drop off' occurred when he had to help out Maric in the ruck later in the game. I reckon as the season progresses, and both Maric and Griffiths become more accustomed to game time and running out matches, we will see him sitting deep for longer and offer up more of what we saw early last night. He'll start to dominate games late as well, is a beast of a bloke.
Barring injury he should be played for all 22 games + finals this year. I don't care if he has the occasional stinker, TV should not be seen over this bloke, ever, period.