Series history says NYCFC in trouble, RSL not done yet

After Leg 1 of the Conference Semifinals, all four series hang in the balance. No club is more than one goal to the good, setting up a tasty set of second legs this week in the Audi 2018 MLS Cup Playoffs.

The home teams won two of the four games, with the Portland Timbers and Columbus Crew SC taking leads into the second 90 minutes. Real Salt Lake played Sporting Kansas City to a draw and NYCFC fell at Yankee Stadium to Atlanta United

FiveThirtyEight has already run through the numerical probabilities, but what about the historical precedents for these scenarios?

Since MLS instituted the away goals tiebreaker in 2014, the worse seed has won the first leg of a series at home by one goal five times, but has only advanced twice. When the two teams draw, the better seed has advanced four out of six times. When the better seed wins the first leg on the road by one goal, they've advanced all three times. 

Leg 1 host
Up 1 goal
2 of 5 (40 pct)
2 of 6 (33 pct)
Down one goal
0 of 3 (0 pct)

In other words: more good news for Atlanta and hope for the Red Bulls and RSL.