These are all of the Capitals' picks in the 20-30 range from the past 10 drafts:

2001, 2002, 2003, 2007: no picks

2004: Schultz (27), Green (29)

2005: Finley (27)

2006: Varlamov (23)

2008: Gustafsson (21), Carlson (28)

2009: Johansson (24)

2010: Kuznetzonv (26)

Of these eight picks, five have made the NHL, with a sixth looking very likely in Kuznetzov.  And all of those five have not just made the NHL, but are at minimum good NHL regulars, with Green already being a star and Carlson and Varlamov having star potential.  Obviously, Finley and Gustafsson appear to be poor picks, but overall, 3/4 of these picks look to be successful.

Let's compare that to other teams' drafting in the 20-30 range.

I classified the players in the following manner:

• bolded and italicized: top player by my judgment
  
• bolded: NHL regular judge by games played in comparison with the amount of time since they were drafted.  A skater had to have played more games than the years since drafted minus four (to account for the time it takes for players to reach the NHL) x 50, which is the minimum amount of games a regular NHL player would appear in per season.  So that's 300 games minimum for players drafted in 2001, 250 for those drafted in 2002, 200 for those drafted in 2003, and so on until 50 for those drafted in 2006 and 0 for 2007.  For goalies, I used the same formula except I multiplied it by 30.    Obviously, games played would be a lousy measure of higher levels of performance, but it works for this purpose.
  
• italicized: players who do not meet the above criteria but are considered to be successful, are late bloomers, or to still have potential in some manner.  Again, I used my judgment for this.

Note: the statistics next to the players name are not necessarily complete.

2001:

2002:

2003:

2004:

2005:

2006:

2007:

It's much too early to judge players from the following drafts, but I have included them for completeness, and bolded the names who have appeared in the NHL.

2008:

2009:

2010:

In total, from the years 2001-2007, 77 players were drafted between 20-30.  Less than half (36) have had at least some type of NHL success.  8 of those can be considered "top" players.

Back to the Caps.  In the same 2001-2007 span, the Caps have had 3 out of 4 players succeed in the NHL.  Even of the more recent picks, the ones since 2008, the Caps have had 2 out of 4 players make the NHL, and 1 of the other ones was only drafted seven months ago.  Green is arguably the best player drafted in this range over the past decade. Thus far, Carlson as the most success of any player drafted in 2008 in this range, and the same is true for Johansson, , although as of now, that's not saying much.  Overall, the Caps have had much more success with draft picks in this range than the rest of the NHL.  And as the Caps hope to be picking in this range every year, this will hopefully be one of the main keys to sustained success.

This also shows why the Caps are very reluctant to trade away these 1st round picks: they're more valuable to the Caps than to pretty much any other organization in the NHL.