The Richards line is so bad that we may have to break up all other lines to fix this. They have been killed possession-wise these entire playoffs, but has been saved by 96% goaltending up until this point. Not tonight though as they were on the ice for 3 out of 4 5v5 Kings goals.
Neither Richards nor St. Louis are good possession players, and Hagelin obviously isn't enough to offset this. The line gets the cushiest zone starts yet still get killed on the shot clock - mostly because they can't defend a lick and concede a ton of shots against.
St. Louis is one of the best drivers of goal scoring in the NHL, but he doesn't drive possession. Put him with Kreider and Stepan to get him some zone time.
Either Nash takes his place with Hagelin and Richards. But if you're afraid that will further reduce the chance of Nash ever scoring you mix up the other two offensive lines as well.
Scenario 1:
Kreider-Stepan-St. Louis
Hagelin-Richards-Nash
Pouliot-Brassard-Zuccarello
Boyle-Moore-Dorsett
Scenario 2:
Kreider-Stepan-St. Louis
Hagelin-Brassard-Nash
Pouliot-Richards-Zuccarello
Boyle-Moore-Dorsett