Draymond Green

Golden State Warriors' Draymond Green gestures after scoring against the Phoenix Suns during the first half of an NBA basketball game Saturday, March 12, 2016, in Oakland, Calif.

(AP Photo/Ben Margot)

A lot of teams regret overlooking Draymond Green in the 2012 NBA Draft before the Golden State Warriors chose him with the 35th pick. The Boston Celtics may be chief among those teams.

With the 22nd pick the Celtics opted for a first-round bust, Fab Melo, who couldn't even convince the team to keep him for his entire rookie contract. A handful of other clubs likewise landed players who left little or no impact, but here's the kicker: Boston's assistant general manager, Mike Zarren, reportedly ranked Green as the third-best player in the entire draft.

At the Sloan Conference this weekend, Brian Scalabrine revealed the ranking:

Brian Scalabrine says MIke Zarren had Draymond Green ranked 3 on his big board in 2012. C's took Sullinger, Fab Melo at 21, 22. #ssac16 — Brian Robb (@BrianTRobb) March 12, 2016

#SSAC16 Scal "Mike Zarren had Draymond Green identified as a top three pick in the draft" "Scal-then why didn't you take him?" — Leigh Klein (@leighalanklein) March 12, 2016

Sports Illustrated's Matt Dollinger added that Zarren put Anthony Davis No. 1 and Jared Sullinger No. 2 in front of Green. It's unclear where Zarren rated Melo.

In retrospect, the Celtics (obviously) should have chosen somebody who didn't walk into a door frame, break a folding chair and let himself fall completely out of shape before his second summer league experience. But they had just selected Sullinger, a safe choice, at No. 21. Considering how many picks flop that late in the first round, and how many bad players followed Sullinger, it made some sense to swing for the fences with an athletic 7-footer, even if Melo's game had some rough edges. A few big names like Green, Jae Crowder and Khris Middleton were taken after Melo, but those guys have all exceeded expectations drastically. Most prognosticators -- with the exception of Zarren, apparently -- thought all three of those players had limited upside.

The draft is unpredictable. Sometimes you stumble into a positionless, 6-foot-7 monster who can defend anyone alive, and sometimes you hope a Brazilian center can learn how to play basketball to match his rare physical tools. You win some, you lose some, and you accidentally let some great ones get away.