Big man Andrea Bargnani hasn't been good on either end of the floor this season. (Ronald Martinez/Getty Images)

By Rob Mahoney

Just before the new year ushers in a clean slate and a boundless optimism, let's examine at the grimmer side of the season thus far: the league's biggest disappointments. Though many of these 12 players figure to rebound, it's worth taking stock of their woes two months into the season. (All stats are through Thursday.)

FIRST TEAM

Andrea Bargnani, Toronto Raptors: After a brief masquerade as a competent defender at the beginning of last season, the old Bargnani has returned to wreak havoc on Dwane Casey's psyche and more than earn the former No. 1 pick his place on the trade block. Bargnani may well lead the league in wide-eyed looks as an opponent's drive goes uncontested, which pairs perfectly with his underwhelming offense to complete a dismal package. An elbow injury will keep him sidelined for a little while longer, but it's becoming increasingly clear that the Raptors' hopes for Bargnani's evolution will go unrewarded.

It's a tired refrain given that Toronto has waited for Bargnani at every stage in his supposed development only to be let down. The Raptors banked on gradual improvement in his work on the glass, but Bargnani's rebounding percentage has slipped this season after years of mild fluctuation. They've assumed that he might convert some nice individual offensive skills into a more cooperative overall game, but he remains difficult to utilize within a balanced team concept. The defensive issues are the most stark of all, and the gap between Bargnani's slow-reacting coverage and defensive mediocrity shouldn't be understated. All that was really asked of him was to become passable on that end, as to better accentuate all that he can contribute offensively. But even that low bar now seems to be a lofty ambition, with a wavering focus the only constant in Bargnani's unreliable defensive game.

Ersan Ilyasova, Milwaukee Bucks: Watch Milwaukee play, and one can see Ilyasova's crisis of confidence in action -- a player who sank 46 percent of his three-pointers last season is pump-faking out of self-doubt. He's starting to score and rebound a bit more, but his shooting percentages haven't fully recovered. Ilyasova's true shooting percentage (which accounts for his threes, twos and free throws as weighted by their value) has dropped by 10 full points, making his bankable 2011-12 season look all the more like an aberration. If that's the case, the Bucks are in for a long four or five years, depending on what they decide to do with him in the partially guaranteed final year of his contract.

Last season's version of Ilyasova (who averaged 17 points and 11.5 rebounds per 36 minutes with a career-high 57.7 true shooting percentage) was absolutely worth the $40 million deal that the Bucks awarded him. But this year's iteration, though still a helpful player, has diminished enough to make such a deal incredibly costly. Teams can no longer afford to dole out such substantial contracts without clear payoff, particularly when the future of the rest of the roster remains so tenuous.

But all of this is looking a bit too far ahead for a player who has actually managed to resurrect his previous form for a few games at a time. Ilyasova most recently had 17 points and 11 rebounds against the Nets, and he managed a five-game stretch of double-digit scoring earlier this month. December has been decidedly more kind to Ilyasova than November was, to the point that I feel slightly guilty for harping on a player who sincerely seems to be on the rise. That said, it's become so difficult to know what to expect from Ilyasova on a game-by-game basis that his season can only track as a disappointment -- relative to both his recent contract and the assumed progress of his 2011-12 season.

Deron Williams, Brooklyn Nets: Regardless of whether you blame Avery Johnson (who has lost his job based on Brooklyn's .500 record) or Williams himself, this has been a lackluster season for a point guard once considered to be the class of his profession. A wrist injury and a meager supporting cast helped explain away Williams' struggles with efficiency over the last few seasons, but reasonably good health and roster renovations now put his errant shooting on display for all to see. He has a big man to work with in Brook Lopez. He has two talented (and very different) scorers on the wings in Joe Johnson and Gerald Wallace. He has the ball in his hands, and now has Avery Johnson's slow-down offense in ruin. It's now up to Williams to live up to his own game, something he hasn't done for a while.

[Ben Golliver: Williams defends himself from criticism after Johnson firing]

Free-agent addition Courtney Lee hasn't paid immediate dividends for the Celtics. (Jared Wickerham/Getty Images)

Courtney Lee, Boston Celtics: Fits between team and player rarely come cleaner than the meeting of Lee, a skilled and versatile combo guard who plays solid on-ball defense, and the Celtics, a team that needed Lee's fill-the-gaps dynamism to boost their offensive potential. Lee may not be prolific enough from the perimeter to replace Ray Allen outright, but he seemed a fitting substitute for a team that has every incentive to get younger and quicker as to best prolong the careers of Kevin Garnett and Paul Pierce.

That's a quaint notion, but hasn't quite worked out in practice. Lee is making a career-low 28 percent from three-point range, and at his absolute best has been a functional stopgap for Boston's second unit. His complementary game has grown so agreeable as to be completely bland, and his most prominent defensive limitations (his inability to body up opponents and fight through screens) are only accentuated by playing with the Celtics' second-unit big men. It's been a hard fall for Lee, and a strange one; I'd bet on Lee's figuring out the proper calibration of his offensive game at some point down the line, but for now he's hardly living up to his presumed role within the Celtics' reboot.

D.J. Augustin, Indiana Pacers: There are players on this list who have merely offered less than expected, but Augustin is one of the few exemplary disappointments who consistently does his team harm. Having a ball handler who is unable to see past the initial defense, consistently create dribble penetration or even get his shot off on the perimeter is brutal -- so much so that Augustin actually weighs down an already underwhelming bench. Playing with the starters more consistently might help some, as would getting Danny Granger back to widen Frank Vogel's lineup options. But for now there is just no possible caveat that can obscure 28 percent shooting from the field from a score-first guard, or the general drag that Augustin puts on the Pacers in general.

(If you're a glutton for a deeper explanation of Augustin's troubles, check out this post.)

RESERVES

Pau Gasol, Los Angeles Lakers: Gasol has all kinds of alibis at his disposal -- a coaching change, knee tendinitis, the absence of Steve Nash/the Lakers actually relying on Chris Duhon, his recently diagnosed plantar fasciitis -- but that doesn't at all excuse his abysmal defensive play. We can forgive some of the offensive issues as Gasol finds his way in a new role under Mike D'Antoni, but the frequency with which he has zoned out and completely missed rotations warrants placement in this bunch.

Manu Ginobili hasn't been able to replicate his terrific 2011-12 season. (D. Clarke Evans/NBAE via Getty Images)

Manu Ginobili, San Antonio Spurs: It may seem odd to talk up the merits of a season in which Ginobili averaged only 12.9 points, but the super-sub had an incredible 2011-12 despite having his season sliced and diced by various ailments. In what was nearly a career low in playing time (due to both injury and the evolution of the Spurs' rotation), Ginobili's creative brilliance was refined to an absurd purity; 53 percent shooting from the field and 41 percent from three-point range is just batty for a player who handles the ball as much as Ginobili does, and yet that was the standard set based on last year's showing. In any general sense, Ginobili is no disappointment this season. But his overall shooting (41.8 percent from the field, 35.7 percent from deep) is depressed even relative to his typical shooting marks, and those scoring explosions are coming a bit less often. Manu's still Manu, but last season's bottled brilliance was clearly something special.

Austin Rivers, New Orleans Hornets: It may not be entirely fair to put a rookie on this list, but Rivers deserves special consideration due to being a lottery pick who has yet to cash in on his single pro-level attribute. Rivers' defense was deemed suspect, his ball-handling shaky and his playmaking a work in progress. But his scoring ability was never much called into question, even though it very clearly should have been. He's getting the playing time and touches necessary to improve, but at the moment Rivers drives with blinders on, scores a miserable 9.8 points per 36 minutes and is still figuring out how to contribute to a team's offense in a beneficial way.

[Ben Golliver: Q&A with Austin Rivers]

Roy Hibbert, Indiana Pacers: Hibbert deserves a pat on the back for his general improvement over the last few weeks, but unfortunately that surge isn't significant enough to keep him off this list. Blame a perfect storm of expectations; a great playoff run, a max contract and an injury to Granger put Hibbert in a position to produce more than ever, but considerable offensive struggles have resulted in career lows virtually across the board. Touch and size have earned Hibbert just 12.4 points per 36 minutes. He's shooting 40.4 percent, well off his previous career worst of 46.1 in 2010-11. His rebounding percentage has dipped slightly and his turnover percentage has increased modestly. Even Hibbert's passing game has suffered, as defenses have become well aware of his difficulties from the field and force him to beat one-on-one coverage -- thereby closing up kick-out opportunities.

That's a brutal mix of statistical regression that has played a rather active role in Indiana's offensive descent. The Wizards are the only team in the league to score fewer points per possession than the Pacers, and though Hibbert hardly deserves to bear the burden of such a ranking alone, he seemed theoretically prepared to assume a larger role in the offense (and contribute more overall relative to prior seasons) regardless of Granger's absence. Perhaps he still is, but for the moment Hibbert is a good defensive center still working to rebuild his offensive game after a recently disclosed wrist injury. That ailment should clearly weigh into our evaluations of Hibbert's depressed numbers, but it doesn't altogether exempt him from blame for his glaring inability to make an offensive impact.

Denver forward Danilo Gallinari is shooting a career-low 39.1 percent from the field. (David Zalubowski/AP)

Danilo Gallinari, Denver Nuggets: Maybe the greater disappointment here doesn't rest with Gallinari, but with our assumptions of linear development. He began his career as a decent scorer who could both shoot from the outside and get to the rim, all while defending with a plucky enthusiasm (even if not with totally sound fundamentals). His production as a sophomore with the Knicks in 2009-10 suggested a talented shot creator with a versatile game, and to some extent that still applies. But even after that promising start, Gallinari's shooting percentages never quite came around, and his scoring has increased only marginally over the course of his career. This season in Denver seemed like a great opportunity for Gallinari to not only command serious minutes but also benefit from the playmaking of both an improving Ty Lawson and the imported Andre Iguodala. That hasn't quite worked out, and Gallinari has posted career-worst shooting percentages (39.1 from the field, 31.7 from long distance) while otherwise maintaining his static -- and decent, really -- levels of production.

Kendrick Perkins, Oklahoma City Thunder: Fair or not, Perkins is a disappointment by way of coach Scott Brooks, who insists on relying on Perk's intangibles at the sake of his team's actual performance. Brooks has grown more flexible and creative over the years, but Perkins is the vestige of his former coaching traditionalism that he can't seem to shed. Opponents are getting better and better at exploiting Perkins' presence on the floor, but OKC has stood by its chemistry and its 28-year-old center.

Perkins is good to have around for defending specific interior threats, but he's a specialist who holds back the Thunder as a second big man. If he's tabbed to play with four perimeter players, so be it. But Perkins lacks the ability to force opponents to defend him, limiting the explosive potential of some of the Thunder's most-used lineups.

Joe Johnson, Brooklyn Nets: