There's not a huge sample to pull from but in my limited NHL viewings, McTavish looked slightly further along than Krebs does right now as a guy just right out of the draft.
The similarities in their game are there, but McTavish in his very limited run with the Ducks to date looked a lot more engaged in the play from end to end.
Then again, this can be a skewed view because Vegas' third line has historically been hit or miss on whether they're a factor or invisible.