I did some checking on the top 100 picks from 2005-2012:

Year 2005 2006 2007 2008 2009 2010 2011 2012
# of players out of football 54 38 42 26 13 9 6 2
1st rd out of football 13 7 7 4 0 1 1 2

The Steelers 2005 draft was nearly as bad as 2008. The only pick that worked was Miller (although one could argue McFadden was an OK pick, he really underperformed for his draft position). So bad draft classes happen, but they obviously have to be followed by exceptional picks in later years. Holmes and Colon saved the 2006 draft. Timmons and Woodley the following year (some might argue the jury is still out on Woodley).