[alnorth]

Here's an example to illustrate what people are saying is momentum.

You are a hitter leading off in the 7th inning, and you are tied 4-4. You were winning by 4-1, but you just lost the lead in the 6th, and now you need to get the lead back.

Meanwhile, in a parallel universe you are the exact same player in the exact same situation in the exact same game facing the exact same pitcher (who just came into the game in both universes), but in this universe you were losing 4-1 in the 6th inning and you tied it up in the 6th. Now its the 7th and time to grab the lead.

Believers in momentum would argue that the 2nd player would do better than the first player.