Since the three pointer was introduced, 87 Guards have had more Offensive Win Shares than Rondo through their first five seasons. Obviously Rondo wouldn't be high in that category due to his lack of scoring, but out of the 87 guards ahead of him, 53 didn't even reach 10 defensive win shares through their first 5 seasons. These players would be considered by many to be very "defensively challenged". The list includes Stephon Marbury, Jose Calderon, Reggie Miller, Kevin Martin, Michael Redd, Mike Bibby etc...
On the other side of the coin there are only 2 players since the 3 Point Line to post more Defensive Win Shares than Rajon. One is arguably the greatest, most complete guard in the history of the NBA, the other is Manu Ginobili. At Rondo's pace he will easily pass Manu and most likely pass MJ for DWS's through 5 years. Does this mean Rajon is a better defensive guard than Michael Jordan was at this point of his career? Not necessarily...
I can hear the arguments already:
"Rajon's Defensive Win Shares have been jacked up because of KG playing behind him."
"Jordan only played in 18 games his second year and didn't have any Defensive Win Shares."
Both are valid points, but I'm not trying to say that Rondo is a better guard than Michael Jordan. I'm trying to say that there is a very short list of guards who have been able to affect the game in as many ways as Rajon does.
Even if you widen the field to All-Time (1946-2011), you still only find 5 guards with 20+ Defensive Win Shares through 5 seasons. It's Walt Frazier, Norm Van Lier, Maurice Cheeks, Michael Jordan, and Manu Ginobili. I don't think anyone can argue that those guys are all excellent defensive guards, and outside of Van Lier they are great all around guards. Rajon Rondo is in that same discussion.