Not saying it's Krejcis fault at all... But if you honestly think we are seeing the same David Krejci these last 16 games that we did the last few years you are off your rocker. Clearly the Bruins bringing in a legit winger has him pumped because he looks like an entirely different player.
I get your point and Krejci looks like a different player. But he is not. The evidence is out there, every time Bergeron goes down and Krejci between Pasta Marchand, he plays like this.
At the same time, I don't want to completely disregard how happy Krejci is playing with hall, but that's what he does with good wingers.
For Krejci to slow the game, the pace needs to be fast in the first place, you get that with speedy wingers and in most playoff games as players play more physical, up-tempo hockey and he thinks faster than opposition skates.
The chemistry with Hall is there and unlike Sabres fans predicted, Hall is not hogging the puck. For what it's worth Hall seems to be smarter than he gets credit for, figuring fast to give the puck to Krejci and be ready to get it back. Playoff Krejci will be something Hall might benefit from long term given the difference in playoff success/experience.
Side note: Both can carry the puck into the offensive zone with no effort. You go forecheck on the blue line? Positional pass to striding Hall. You playing 1 on 1 ? give and go over the blue line.. So far it worked like magic.