Once you control for the other factors impacting the team (players leaving, player development), you do get a positive impact from top 10 recruits. But on average, it is not nearly as large as most people expect.
There are two problems here. First, there are top 10 recruits that were simply disappointing. (Think John Henson for North Carolina or Lance Stephenson for Cincinnati last year.)
Second, consider the alternative. If a top 10 recruit did not show up, they would not necessarily be replaced by a player with a 75.9 ORtg. Top 10 recruits tend to go to programs that have pretty good alternatives. For a quality team like Duke in 2008, what would have happened if there was no Kyle Singler? Well, Taylor King, Nolan Smith, or Brian Zoubek might have earned more playing time. And while Coach K clearly had his reasons for limiting those player’s minutes in 2008, they were all very effective when on the court. In other words, we have a value over replacement player (VORP) issue. For super talented teams, adding a top 10 recruit usually takes playing time away from other very talented players.
