Deron Williams has been shanking frequently. It's been that way for a little while, with Deron going from a .439 field-goal mark in 2010-2011, to a .407 mark in 2011-2012, to where we're currently at with his .382 field-goal percentage in 2012-2013. Howard Beck of the New York Times listed some functional reasons that may account for Deron's shooting woes:
"The source of Williams’s struggles is somewhat elusive, but injuries — including a banged-up right (shooting) wrist and sore right elbow — have surely played a role. He also has a left-ankle injury that will probably require surgery next summer. Williams said it is not the bumps and bruises, but his general comfort level, that is to blame."
These injuries could certainly influence why Deron Williams isn't the .507 shooter he was back in 2007-2008. I would like to posit another reason for his decease in efficiency, though. Take a look at Deron's current shot distribution chart for the 2012-2013 season, and pay special attention to his shots near the rim.
So we can avoid the "small sample size" tag, here are Williams' shots in 2011-2012. Note that under 30% of his tries came at the rim last season.
Finally, take a look at Deron's best shooting season, 2007-2008 in Utah. Back then, he was attempting 43.3% of his shots right at the rim, more than 18% above the clip he's currently logging.
You may also notice that in 2007-2008, three-point attempts only added up to 18.2% of Williams' total shot amount. In 2012-2013, a whopping 38.7% of Deron's shots are coming from distance. Considering that Deron Williams hit .395 of his three point tries in 2007-2008 (he's now hitting .268 from deep), less could be more for Williams.
Deron Williams has roughly maintained the same level of accuracy on long two-point tries, though. In 2007-2008, Williams was 46 percent on long twos, which is only three percent better than his current mark from that range (via HoopData). Williams' free-throw percentage has also held steady over the last two years. Subjectively, it doesn't look like he's shooting any differently than he used to.
The problem, as I see it, is that so many of his attempts happen far from the rim. It could be a matter of diminishing athleticism, but I would hazard that offensive scheme has its impact. In the flex-cut Jerry Sloan system, Deron Williams received screens below the three point line, as part of a constantly moving offense. This allowed for many driving lanes to the rim, many shots at the basket.
With the Nets, Deron Williams more often finds himself in isolation, dribbling above the arc. Sometimes, shooting well has little to do with your shooting form. This could be one of those instances.