Transfer Portal I wish Vargas well but all that glitters is not gold.
At Davis, he would have gotten lots of playing time at RB, and the opportunity to improve his game, blocking, catching out of the backfield, and most important, ball protection. In addition, he could have worked on special teams (like Lan) to increase his value when the NFL draft comes knocking.
At Cal, my guess is that they will expect results and will be much less forgiving for any mistakes. May find himself watching more of the games at Cal than playing in them at Davis.