OK, I am lying.  Frankly I had no idea who Lin was until a week ago. So, no, I did not know that Jeremy Lin was this good. But frankly, that's irrelevant. One did not have to know Lin would play this well to keep him. Let me elaborate. When I read Daryl Morey's recent tweets on Lin, I had to laugh a bit:

@dmorey @jlin7 is a very good player but Linsanity was not happening here this year RT @cforcsar Lin, do we regret it that we waived him?

@dmorey We should have kept @jlin7.Did not know he was this good.Anyone who says they knew misleading U RT @trane711 Just accept the@jlin7 mistake

This all reminds a lot of Moneyball, in the scene where Billy Beane (played by Brad Pitt) argues with scout Grady Fuson (played by Ken Medlock) about how to evaluate players. And Pitt says: "You don't know, Grady. I've been in the room with you, I've watched you sit there with these young kids and tell them that you know they'll be a star some day, but the truth is, you don't know." This argument never happened in real life, but it appears to accurately reflect Beane's general attitude that it was important for scouts and GMs to stop pretending that they knew how players were going to turn out, and instead concentrate on acquiring players where the probabilities are on your side and then hope for the best.

So, when Morey says "Anyone who says they knew is misleading you", well, he's being rather disingenuous.  Because no NBA coach, general manager, scout, etc, ever knows a young, untested player will become a star, any more than an analyst does.  As David Berri said recently, "No one knew this player would be this good" is a sentence you could say about nearly every NBA player (It has since occurred to me that Shaq might be the exception). And since you cannot know, one's job as an NBA general manager when deciding whether to keep or waive a young player is not to question whether or not one knows how good he is, but simply whether or not he's worth giving playing time to. Ok, I'm going to stop bolding the word "know".

It turns out there are some people that thought he was worth giving playing time to. When Arturo Galletti evaluated the 2010-11 rookies (based on that pre-season and a couple of weeks of play), Jeremy Lin ranked 18th, having a WP48 of 0.091, which is very good for a rookie (most rookies do not achieve average-level performance). Also, the folks at Golden State of mind noted that Lin was a very good college player:

The list above ranks the undrafted rookies based on their PAWS40. PAWS40 is the best metric in evaluating how a player's production translates from college to the pro's.  If you want to look at how college production translates to the pro's click here.

To summarize, players with a PAWS40 of 13 have a good chance at becoming an above average player (WP48 of .150). Guess what Jeremy Lin's PAWS40 is? 12.9.

But Morey's decision had the benefit of even more information than these two, since he made it a year later, after Lin had played 300 minutes of basketball in the NBA (and, as mentioned today on The Wages of Wins, about 600 minutes of D-League ball). And for all you rocket scientist GMs out there, I hate to break it to you, but after the 2010-11 season, there was simply no question at all, Jeremy Lin was definitely worth giving another look. If you cut him before giving him that look, you made a mistake, and it's that simple:

Relative to the average PG, in very limited minutes, Lin was better at rebounding, turnovers, blocking shots, steals, and getting to the line (note that he took fewer shots but was average at getting to the line anyway). Again, these are very limited minutes.  But they are very good minutes. One has to wonder, why weren't coaches willing to give him more minutes?

After all, coaches are full of rhetoric that goes something like this: "if you play hard and work hard, you'll get your chance." Well, Jeremy Lin went out and played hard.  He grabbed boards, he made great defensive plays. He played smart and didn't turn the ball over much.  He didn't shoot very well, but then shooting is the part of player performance most susceptible to variance; one would think any NBA-caliber coach would know this. A lot of coaches love to play lip-service to the theme that if you make hustle plays, they'll find time for you.

And again, I'm not claiming that I knew Lin was going to be a good player. But I am claiming he deserved more minutes so that the folks in charge could find out more.  There's no question in my mind that a GM who was truly ignoring sunk costs would have waived Jonny Flynn (who's been absolutely terrible in a lot of NBA minutes) instead of Jeremy Lin. But since Flynn has a guaranteed contract and was a high draft choice, I suspect the waiving of Lin wasn't entirely about "basketball reasons".