Home field advantage in rugby has become a thing. BYU hasn't ever lost (to my knowledge) at South Field to a college team. It would be much tougher to beat Cal on their turf. The last 4 NCs have been in Utah.

In 2012, Cal didn't compete for a NC because they had gone on their own before we did. We beat Arkansas State (after beating Life in the semifinals). This began the run of NCs for BYU.

In 2013 and 2014, after BYU joined Cal and formed the Varsity Cup, Cal had some bad injuries both years that depleted them by the end of the season. No excuses or anything, but we were a lot more healthy compared to them.

At some point, Cal was the only program to have players receive private scholarships. I believe they did away with that.

Lastly, I think BYU took advantage of momentum given and now has the fan support and sponsorship it needs to be the national power.