Most would agree that it's tough to answer that question after just one season.
Also, McCourty has some very strong competition among the likes of Richard Seymour (2001), Ty Warren (2003), Vince Wilfork (2004), Logan Mankins (2005) and Jerod Mayo (2008).
One could make the case McCourty had the best rookie season of any Patriots first-round pick in the Belichick era, starting all 16 games and finishing with seven interceptions, the second highest total in the NFL. But Mayo, the 2008 Associated Press Defensive Rookie of the Year, might have something to say about that. Ditto for Mankins, who started all 16 games in his rookie campaign.
When it comes to voting for the best first-round pick in the Belichick era, maybe it's best to split the vote into two categories -- the first-half of Belichick's time in New England (2000-2005) and the second half of Belichick's time in New England (2006-2010).
Vote in the polls included in this blog entry, and share thoughts in the comments section of this blog entry.