Dantonio took over at Cincinnati in 2004 and stayed until the end of 2006 so looking at this beginning in 2002 (the last full year before he got there) and until 2010 (Kelly's first year at ND) here is what you get.
2002 - #95
2003 - #84
2004 - #75 (Dantonio's first class)
2005 - #70
2006 - #70
2007 - #80 (First year in the Big East - Kelly's first year)
2008 - #45
2009 - #53
2010 - #62
So Dantonio inherited a team whose two previous classes were 84 and 95 and he managed to get them into the 70s while also playing Conference USA. Kelly continued the trend after his first year, however this also coincided with their move to the Big East. You could make a strong argument that their new conference affiliation had as much to do with uptick in recruiting as Brian Kelly did, if not more. Usually when teams move up in Conference Affiliation their recruiting also tends to pick up (Texas A&M, TCU, and Missouri have shown signs of this) so I think it is pretty weak to say UC was able to draw in more recruits based solely on what Kelly was doing.