In thinking about it, the game has changed a lot over the last ten year, and a lot more points are being scored these days, so a simple comparison makes things look worse than they are. I decided to go back and add one more column to this table, a comparison between the points given up per game and the median for other teams that year:
Year, Avg Points, Total Defense, Comparison to Median team that year
2000 18.9 349.3 -24%
2001 29.4 444.6 +15%
2002 31.2 377.8 +21%
2003 31.0 369.8 +24%
2004 24.6 319.6 -3%
2005 30.5 452.5 +19%
2006 18.1 302.9 -20%
2007 29.9 362.8 +12%
2008 27.2 348.6 +10%
2009 21.3 348.5 -16%
2010 23.8 353.4 -8%
2011 22.1 361.4 -15%
2012 24.8 388.8 -11%
2013 27.5 405.8 +5%
2014 24.8 394.3 -7%
2015 25.3 377.7 -7%
2016 22.6 360.2 -19%
2017 24.2 371.6 -9%
2018 24.6 390.9 -1%
2019 30.7 460.0 +14% (through 7 games)
By adding the third column, the best defenses relative to other defenses that year was 2000 (-24%). The best under Solich were 2006 (-20%), 2016 (-19%), 2009 (-16%) and 2011 (-15%). Those four years are also his four MAC East Championships. 2018 does not do that well, at -1% despite their strong finish because they started the year horribly.
As for 2019, by this measure it is better than 2005. If they finish strongly this year, as last year's defense did, they could improve their rank considerably.
“We have two ears and one mouth so that we can listen twice as much as we speak.” ― Epictetus