This actually doesn't do the improvement justice. It actually started to improve fairly dramatically IMO from 1999 - 2004. The problem was that you actually had to understand volleyball to recognize it, and they were measuring improvement in things like points scored. 1998 was the season coached by Kerry Miller who turned out to have falsified her resume to get the job. She was never all PAC 10 and never recieved a degree from Arizona. She was also the focus of at least one law suit against the university for abuse towards the athletes. They figured it out during the season and ended up letting her run the season out before firing her at the end. That was just 3 or 4 seasons removed from an NCAA tourney appearance. I would guess that in 1999 there wasn't more than 1 or 2 (if that) D1 vb players on the roster. To really see the improvement you have to actually look at things like hitting percentages and points scored. In 1999 for instance against Nebraska (a very pedestrian NU team only rated #10) they scored 2 points in a 3 game loss (under the old side out scoring method) (Insert audible moan of pleasure from DaddyMac as remembers fondly the old scoring system). They lost 15-0, 15-2 and 15-0. They only scored 11 points total in the second match that year when NU played the second team significant minutes, another three game lose. In 2000 they scored a whopping 26 points in two 3 game loses, and even got NU to take a time out (a stated goal of the team that year I believe). This was a #1 ranked national championship NU team. Then they switch to rally scoring the comparisons get a little more difficult. Don't get me wrong. They were not good when CLJ got here but 5 years before that they couldn't have beaten the vb team from the DMACC school of trucking.
As for the WBB comparison it's really apples and oranges, but the big thing that keeps a program like ISU from breaking through to the top 10 is Title IX itself. Title IX doesn't reward quality just quantity. As such in WBB you have 15 scholarships, where as in WVB you have 12. Especially in NCAA qualifying field those extra 3 scholarships allow the top teams to horde talent. That single rule makes it a lot more difficult to break in to the top ten consistently in WBB, than in WVB. It also makes it that much more difficult to see the rise of the mid majors in WBB that you've seen in MBB.
For me I just enjoy the fact that both programs are so enjoyable to watch.