Why didn't we set the middle more
Simple - passing. It is risky and difficult to successfully execute a first tempo set with a less than perfect pass. It takes an elite, confidant setter to attempt such a connection with her middles.
Most college teams score their passers on a 3 point scale. A "3" pass is nearly perfect, both in location and tempo, and theoretically offers the setter all 3 front row hitters as options. A pass that pulls the setter far enough from target to take out the middles as options, leaving only the OH and RH, is deemed a "2." A pass that is bad enough so as to only leave high outside as an option is scored as a "1." Of course, the defense recognizes "1" passes as well, and will have 2 or 3 blockers camped on the outside hitter. And the opposing back row will have more time to set up and dig balls from the areas to which the block funnels the attacks. Now this methodology was developed before pipe attacks and other back row attacks that are now common, but is still widely used.
Most teams will strive to pass at a 2.6 - 2.7 average, which is obviously easier to aspire to than it is to achieve, but should allow them to run a multiple tempo, multiple option attack that keeps the defense guessing. Most teams also aspire to side out at least a 60-65% rate. This recognized so much that it is often included in box scores (see below).
http://www.cyclones.com/pdf9/4170607.pdf
As you can see, the only set ISU lost to Baylor was the 3rd, when Baylor sided at 57%, and ISU at 45%. And of course, ISU sided out at 60, 64 and 63% in the 1st, 2nd and 4th sets and won the match. And of course, it is much easier to recognize these in retrospect than it is to coach and execute a successful serve receive against a team of elite athletes serving bullets at your kids.