I disagree entirely on the idea that teams have to be equal on wins or championships for something to be a rivalry. I think there are a lot of other things that can make for a rivalry.The only really good point I thought you had SBoyd was the fact that the rivalry was one of the oldest in baseball. History is a big part of rivalries. I think the Marichal and Roseboro thing was pretty on par for a rivalry thing. Every rivalry starts somewhere, and it's usually with a fight.There's a few different types of rivalry. Some teams are rivals just because of the playoffs, like the Lakers and Celtics, but some are rivals just because of a fight or verbal altercation between the players or fans. Some are rivals because one is the underdog that ruined the bigger team's perfect record or whatever. There are definitely teams that are rivals because of a record during the season or a playoff matchup, but not all of them. I think the Red Sox vs. Yankees thing is a huge rivalry... like yankshater posted, there's pretty much a laundry list from the last 5 years of things they've done, and that's just the last 5 years.My personal favorite has to be Texas A&M vs. texas. People bring up 0klahoma vs. texas all the time, because they've had good teams recently. But you just can't match branding 13-0 on an opponents mascot. That's jawesome.