"Momentum" is a term used by sportscasters to keep us interested in a losing team that is showing signs of a comeback. It has almost no relevance at all to a sport which is almost purely individual like tennis or major league baseball.
It has almost no relevance at all to a sport which is almost purely individual like tennis or major league baseball. While I can see baseball may not be as much of a team effort as football or even basketball, it is still very much a team sport, especially on the defensive side. Even on the offensive side, there is teamwork involved. Sacrafices, hit-n-tuns, stealing bases, breaking up double plays....