Pasta is a world Class superstar and he belongs on the first-line. Its the best line in Hockey !
The second line of Krejci centering Jake and MoJo has looked great and each passing day will build more and more chemistry, no need to tear it down.
Putting Heinen on the third line with Coyle makes that line that much stronger. Heinen is a cerebral player who can play with just about anyone and is very defensive responsible as is Coyle and whoever they decide to play on the right-side the Bruins will have four strong lines.
You finely find a winger who plays with Krecji and Jake and you want to separate it already and at the expense of breaking up arguably the best line in hockey
It may have made some sense if the second line wasn't clicking but that is far from the case.