For me , it's a fluid definition. It can change with the era and the league. Right now, this league is trending youth, speed and skill. the Pens getting bonino and Haglin at the deadline 2 years ago, cemented their Cup run. NO team could match that 3rd line. Other GM's saw that and that changed what 3rd lines used to be. The big heavy game that used to be in vogue , isn't anymore. I've watched the Bruins transgressing over the last 3 of 4 years and this year they do have youth with skill and speed. THey are an example of a 'big heavy team' who had a rep for that for decades, realizing the league changed. They are faring well this year and McAvoy is a stud, along with Carlo, they have a solid twosome for the future on the blueline. I'd love to see McAvoy win the Calder but I Think Matt Barzal's to lose, if he stays healthy, he's a stud.
The Kings in 2012, for me, in that time, were a team 'built for the playoffs'.
They underachieved dramatically during the regular season and then when that puck dropped in Vancouver in April, Mike Richards showed why DL brought him to town and showed them what you need to do to win. From that point on, they never looked back. They had elite goaltending, 6 healthy defenmen for the entire 2 month run (rare!) Ridiculous center depth (Which you need to win, it's crucial) and every forward had a role, knew that role, accepted it and played it to hilt. They had an insatiable hunger to win.
They also had a ridiculous amount of leadership, which was as important as any recorded stat. I've seen teams overloaded with talent (like the Caps were for years) that rack up reg season points but when April comes, they die on the vine.
No leadership.
So for me, built for the playoffs can change according to where the NHL is. Right now , it seems to be built on speed and attacking with it. And the Bolts are in the driver's seat, if they stay healthy, I can't see anybody beating them 4 out of 7.