Things can change awfully quickly in the world of MLS single-elimination playoffs.
The Philadelphia Union found that out the hard way. Fresh off winning their first Supporters' Shield, they were set up nicely at home (where they hadn't dropped a point in nine games all season) and drew a team against whom it had gone 3-0-1 in the regular season and eliminated from the MLS Is Back tournament. Two New England goals in a four-minute span later, and the Union and their Shield-Cup double dreams are toast.
That's just the latest example of the MLS playoffs caring not about what occurred in the regular season.