This question comes up a lot: do teams need to have "momentum" going into the playoffs? In other words, if a team loses its last few games of the year, is that a bad sign for the first round of the playoffs?
To answer this question, I went back over the last five seasons and calculated every team's "goal percentage", that is GF/(GF+GA), for the first round of the playoffs. I then worked my way back through each team's entire 82-game season and calculated that same "goal percentage" for the final N games of the season and ran a linear regression between the regular season outcome and the playoff outcome at each step. Here you can see the regression coefficient and the R^2 for the predictive value of regular season performance:
In a word, no, late-season performance does not have predictive value for the first round of the playoffs. If you want to start worrying, you really want to look back at least 35 games.