With this core, the Pittsburgh Penguins have won an impressive three Stanley Cups, but as the group ages, they realized they encountered one major problem on the back end.
This is something that was cured greatly with the acquisition of Karlsson, as it added plenty of speed to the blue line, giving them another player that can put plenty of pressure on opposing teams.
Sure, Karlsson will give them more speed and offensive firepower, but with an ageing group, this could potentially be their final run, so expect to see them throw everything into this season.