Looking at only NIT champions is a pretty small sample size. NIT champs is also pretty meaningless, nobody cares about those games, so I'm positive there have been some pretty shitty teams win the whole damn thing. I'm sure there have been plenty of NIT participants who have ended the next year in the rankings. Too lazy to look it up.
A couple of things, you forgot a very important qualifier that I placed on my first post which was being NIT Champs and losing your leading scorer. It's pretty ridiculous to think that you made the NIT and then will finish the top 25 in the next season while going into a rebuild. In Baylor's case they are losing the player who had the greatest statistical season in the history of their school. Also you overstate just how difficult it is to finish in the final top 25 poll. We didn't finish in the top 25 in 2007-08. Oh BTW the teams absolutely care, don't be absurd.
Anyway I did the research for you because I made a point and I needed to know I was right and I was.
I extended the search for NIT teams to the NIT final four, a bigger sample size and frankly it would be fruitless to go any further because lets face it outside of an extenuating circumstance which in this case is either getting a really good player or returning a really good player from injury which won't apply to Baylor next season. Another note before I give the list; 2008-09 K-State made the NIT but didn't reach the NIT Semifinals. Of course K-State made the NCAA Elite Eight the next season but we returned all but one starter, Darren Kent, and replaced Kent, Buchi Awaji, and Fred Brown with JO, Rodney, and Tay.
Anyway the only team I found since 2000 that fit the criteria of making the NIT one year, rebuilding and then finishing the next season in the top 25 is the 2010 UNC NIT team. That 2010 team was essentially the leftovers from their dominant 2009 National Championship team. They lost Ty Lawson, Psycho T, Wayne Ellington, and Danny Green. They were left with nothing. The 2011 team featured the #4 signing class in the country including two lottery picks in Harrison Barnes and Kendall Marshall.
The other teams who finished in the top 25 after making it to Madison Square Garden are
2010 Baylor- They returned leading scorers Lace Dunn and Tweety Carter from the 2009 NIT team and added Epke Udoh as a transfer
2008 Clemson-Returned 4 starters including the leading scorer and 4 out of the top 5 scorers from the 2007 NIT squad
2007 Louisville-Brought back 3 leading scorers and 4 starters from the 2006 NIT Semifinalists
2006 Memphis- Returned the 2 leading scorers and added the #7 recruiting class including Chris Douglas-Roberts from the 2005 NIT team
Love these last 3
2003 Syracuse-Returned 3 starters and leading scorers and added Carmelo Anthony and Gerry MacNemera from the 2002 NIT team
2002 Alabama- Returned their entire starting 5 from the 2001 NIT team, also worth noting that NIT team had Gerald Wallace on it and he didn't start and only averaged 9 PPG.
2001 Notre Dame- They returned the first 9 players in scoring and minutes from the 2000 NIT team
So in summary 1 NIT team has lost their leading scorer from the previous season and finished the next season in the top 25 and they had to sign two lottery picks to do that.
3 out of 13 winners made the top 25 regardless of who they returned and 8 out of 39 of the remainder of the semi-finalists did the same for a total of 11 of 52 NIT semi-finalists since 2000 have made the top 25 the next season. Knowing this, it seems Iowa is best suited to finish in the top 25 next year of all of the four semi-finalists. Obviously we know Kentucky is highly likely to finish in the top 25 next year because of their signing class. It is worth noting though that they are likely to return their 2 leading scorers from this season.
Oh one last note, as I suspected broadening the sample size had an adverse effect on the percentage of teams that made the top 25; 23.0% of NIT champs made the top 25 next season while 20.5% of semi-finalists did the same. Common sense will tell you that the more garbage teams I pull into the sample size the less they are likely to be considered amongst the elite the next season.