The one on the baseline was reasonably close, but you're right, the one on the side that landed one foot out of bounds and literally 3 feet in front of the ref, that she called in, was perplexing. The fact that they had to waste a challenge on it was frustrating. It didn't matter in this match, but that challenge was Cook's last, and if the match extended past three sets, they would have been at the mercy of the calls in play.
I don't get to see them much on TV, but they really make it difficult on their opponents from a defensive perspective. The Huskers dig out shot after shot---it's enjoyable to watch. And it's not just the libero making crazy digs, there are multiple players laying out and keeping rallies going. They also have several players that really stress the opponents with their serve. Many times that first dig by Michigan (and Michigan State on Friday) was not clean, preventing them from getting into their offense.
I was really impressed by the way the Huskers blocked against Michigan. I don't see them much, but that was the best blocking effort I've seen this year.
Purdue is the last ranked (as of today) opponent that Nebraska plays before the tournament. They are up next. Getting two wins on the road was key (particularly MSU), and if they beat Purdue, the odds of a B1G championship go way up. Nebraska has the tie breaker over Penn State, and Penn State still has games against Michigan State, Minnesota, and Wisconsin.