It is really about how many plays did you make good progress towards a first down. For example, if it's 1st down and you get 40% the yards you need to get the next first down, that is considered a successful play. A successful third down is one where you convert and get a first down.

Net success takes this metric for both our offense and the opponents' offense and subtracts them.

Upshot is: Baylor did a better job of reliably chugging along and picking up first downs. We got more points because of dramatic turnover plays/special teams plays/big plays/etc.