In my mind, a 2nd overall pick should be special regardless of the position.
Why have you developed that opinion? Truly special players (e.g. Peyton Manning, Lawrence Taylor) don't show up in the draft every single year. I think you'll find that it's more like two or three every decade. Now if we're talking Pro Bowl caliber players, that's a little different. Ronnie Brown certainly underachieved, but a lot of that had to do with injuries. There were several seasons where he was playing at a pro bowl caliber level only to have it up ended by an injury (2007 and 2009). Hindsight says that Ronnie Brown was not worthy of the #2 overall pick. But when the pick was made, Brown certainly was worthy of the #2 in terms of talent and potential. His play prior to the injuries prove this.
BTW, here are the top 2 picks from the last 10 drafts (previous to this past one). How many of these players are truly special? 3 or 4? And that's out of 20.
2010
1 St. Louis Rams Sam Bradford QB Oklahoma
2 Detroit Lions Ndamukong Suh DT Nebraska
2009
1 Detroit Lions Matthew Stafford QB Georgia
2 St. Louis Rams Jason Smith T Baylor
2008
1 Miami Dolphins Jake Long T Michigan
2 St. Louis Rams Chris Long DE Virginia
2007
1 Oakland Raiders JaMarcus Russell QB Louisiana State
2 Detroit Lions Calvin Johnson WR Georgia Tech
2006
1 Houston Texans Mario Williams DE North Carolina State
2 New Orleans Saints Reggie Bush RB USC
2005
1 San Francisco 49ers Alex Smith QB Utah
2 Miami Dolphins Ronnie Brown RB Auburn
2004
1 San Diego Chargers Eli Manning QB Mississippi
2 Oakland Raiders Robert Gallery T Iowa
2003
1 Cincinnati Bengals Carson Palmer QB USC
2 Detroit Lions Charles Rogers WR Michigan State
2002
1 Houston Texans David Carr QB Fresno State
2 Carolina Panthers Julius Peppers DE North Carolina
2001
1 Atlanta Falcons Michael Vick QB Virginia Tech
2 Arizona Cardinals Leonard Davis G Texas