You can't have ever played competitive sports if you think this is even close to being true. A team plays mostly division opponents through the season, and if the division is weak you can have a great record without being a very good team. Playoffs are far more intense, both with the schedules, the caliber of the competition, and the pressure.
I agree with what you're saying. There are players that rack up a ton of points in the regular season yet disappear when the games mean that much more. Joe Thornton and Alexander Ovechkin are just two examples. The regular season is the entree while the post season is the main course. Players don't become professional to win regular season games, they do it so they can win the ultimate prize. Whether that be a World Series, a Stanley Cup, it doesn't make any difference. The true players will step it up in the postseason while the "pretenders" will always find a way to disappear when the games truly matter.
And what I love the most is that
anything can happen! True, luck
can play a factor, but the truly good teams will be able to persevere from a bad bounce or a missed call. A lot of the regular season dynamos will let that eat at them and the series will be lost. Skill and luck go hand-in-hand. That's always been the case with professional sports. You can't have one without the other.
Look at the San Jose Sharks. How many times did they win the President's Trophy for best regular-season record and end up getting punted in the first round(almost every year, last year was one of the few exceptions) to the 8th seeded team? That was because the 8th seeded team battled and fought to make the postseason and they were more hungry for it while the Sharks would usually coast for the final month of the regular season and end up being less prepared than they should have been. Heck, the winning teams don't even want the President's trophy and refuse to touch it due to superstition. That isn't the trophy they want. They want the Stanley Cup.
My post was a little more full of rambling that I had first intended, but my point still came across.