Blatche is having a good season, but I think it's a bit over-the-top to say that it was a "big miss."
People need to remember that this is a player who had been in the league for 7 seasons, and had been largely terrible in ALL of them. There is a reason that he was sitting on the scrap heap for the vet's minimum. There was no reason in the summer that we should have signed him. Yeah, in retrospect, it looks like he improved his game enough that he would have been a great addition, but that's just hindsight talking.
He is having a career year in points, rebounds, steals, shooting percentages, etc. We don't even know if it is sustainable yet, for all we know he will regress for the rest of the season. But still, we are talking about a complete out-of-nowhere renovation of his game. So it's disingenuous to say that it was a "big miss," because based on the way Blatche had played the last 7 seasons there was no reason to want him besides size.
It's like people harping on Danny Ainge accusing him of screwing up by not drafting Deandre Jordan. Yes, with hindsight, we can see that it might have been a good call, but he was drafted in the 2nd round, so literally every other team in the league passed on him as well.
That's the whole point of a surprise draft pick or a surprise MIP-candidate, it's a SURPRISE. Every team passed on Blatche, reasonably considering his career up to that point. The Nets took a gamble, and it ended up working out because he had an amazing turnaround in his level of play. They got lucky. It happens sometimes. But then using it as a flimsy excuse to attack Danny Ainge for somehow not being able to see the future is pointless.