[Basel A]

The difference between FIRST and many sports teams is that in most sports, the players are the major deciding factor in how good a team is, then the coach. Both of these are quite temporary. Dissimilarly, in most of what you call "dominant" teams, there's a foundation of dedicated mentors who don't move.

Though there are the fans and such that stay behind a sports team no matter what, they are not the deciding factor in how good a team will be. However, in FIRST, it is often the mentors that will determine how good a FIRST team is over the years (obviously a highly talented/highly dedicated/etc. student can have a major influence on a team, but in most cases they will move on to another team or just graduate after only 4 years).

As a note, this isn't saying those teams have dedicated mentors who build the robot, merely saying that those mentors do a great job in training students in such a way to be successful in FIRST, whether in decision-making skills or copious design "suggestions," those teams are more successful for it.