Bruce Weber’s team is underachieving this year, and, as a result, he’s been switching things up. He had the team elect new captains; he has changed the starting lineup. Since those shakeups following a loss at Northwestern two Saturdays ago, Illinois has won three straight, but victories over Penn State, Indiana and Iowa haven’t done much to stem growing concern that this is becoming a lost season for the Illini. It’s tricky to parse the numbers, but Illinois may be making some real strides to reverse one negative defensive trend that has plagued UofI this season.

Expectations: This appeared to be a “hold-water” year for Illinois in the fall. Weber had lost solid distributor and defender Chester Frazier, spot-up shooter Trent Meacham and the versatile Calvin Brock from a team that achieved a No. 5 seed in the NCAA Tournament last season.

The additions of two four-star guards, D.J. Richardson and Brandon Paul, as part of a nationally-ranked four-player 2009 class seemed likely to prevent much regression as Weber awaits his most acclaimed class in 2010. In 2010-11, Richardson and Paul are to be joined by three of the nation’s top prep players, including small forward Jereme Richmond. Weber will also have his top three returners entering this season — Demetri McCamey, Mike Davis and Mike Tisdale — back for their senior seasons. It would appear to be a fortuitous confluence of talent in what many expect will be the season of Illinois’ re-emergence as a Big Ten power.

And that brings us to this year, the year between. Fans rightly expect a repeat NCAA Tournament appearance in 2010, even if a deep run appeared unlikely at the beginning of the season. Losses to Utah, Bradley and Georgia out of conference were confusing in that they were juxtaposed to wins against Clemson and Vanderbilt, teams that are of a far higher caliber. The Big Ten season brought a 4-0 start, followed by three straight losses and now three straight wins. The 7-3 record is sexy, but that six of the wins have come against the leagues dregs — and the other was at home in overtime to Northwestern — hasn’t escaped anyone’s attention in Champaign. With the meat of the schedule ahead — expect Illinois to be the underdog in seven of its next eight games — let’s look at what’s gone right and what’s gone wrong for the Illini in 2009-10.

The offense is better: Along with Tisdale’s emergence as a top post scorer, Paul and Richardson have added offensive diversity to Illinois’ attack. McCamey has shot more often and improved his efficiency by making about four percent more of his 2- and 3-pointers. His combination of 2-point makes and assists means he’s not dissimilar from Evan Turner, though Turner is a bit better at each and has four inches on McCamey, which is much of why the Buckeyes star is a far better rebounder.

Richardson has been able to replace a lot of what Illinois lost with Meacham’s departure — efficient 3-point shooting — and Paul has shown a great willingness to eat up many possessions, even though his affiance (43.1 percent eFG) probably doesn’t warrant that many looks. Tisdale has become a dependable and proficient option in the post, and his free-throw shooting (84 percent) are a good match for a player who gets fouled a lot. Davis has plateaued after a breakout sophomore season, though he still remains a positive on offense.

It’s primarily for these reasons that Illinois has gone from 10th to sixth in adjusted offensive efficiency in the Big Ten. That’s the good news.

The defense is worse: One of the most difficult things about a statistical evaluation of a sport that doesn’t have very many discrete events — unlike baseball, for instance — is that it’s often hard to isolate the influence of an individual player on events, and that’s especially true of defense in basketball. Steals, blocks, fouls and defensive rebounding each gives us a piece to the puzzle, but those pieces don’t form a coherent whole. What we do know is this: Illinois’ defense has fallen from first to seventh in the Big Ten in adjusted efficiency.

The departed Brock and Frazier were two players known primarily for the things they did well besides score. Brock was a terrific offensive rebounder for his size and would grab his share of steals. Frazier was a strong distributor, and he, too, would get some steals. Indeed, Brock and Frazier were the two best thieves on the Illini team, and Illinois has seen its turnover rate damaged as a result. Paul would appear to have replaced most of the steals gap, but there is still a gap. The Illini are forcing about two fewer turnovers per game, a change that has dropped Illinois from fourth to eighth in the conference in percentage of opponents’ possessions that end in turnovers.

Illinois is a bit more liberal with fouls this season but also a bit better on the defensive glass, and those factors likely even out. The one thing that is hard to explain is why Illinois’ two-point defense has suffered this season. Illinois was one of the elite field-goal defensive teams in the country last season because of its ability to suppress percentages on both 2-pointers (35th in the nation, 44.1 percent) and 3-pointers (seventh, 29.6). This season, Illinois is again a dominant 3-point-defending team (17th, 29.3), but the 2-point defense has slipped (123rd, 46.5).

The question is why. A defense’s ability to hold opponents to low 2-point percentages is tied closely to the height and shot-blocking rates of the defense. Illinois is both taller and blocking more shots this year, and yet the 2-point defense is worse. Part of the problem is the ineffective height of Davis. At a lanky 6-foot-9, one would expect him to be a shot-altering presence, but he has just 11 blocks in 22 games.

But it’s not just Davis’ lack of blocked shots that are problematic. As I mentioned, Illinois is blocking more shots than it did last season, thanks mostly to Tisdale. Illinois has gone from fifth to fourth in the Big Ten in shot-block rate but third to eighth in 2-point defense. Something isn’t adding up.

When the pieces don’t add up, that’s when we see coaches making changes. After Illinois allowed Northwestern to convert on 14-of-24 (58.3 percent) 2-point attempts in that Jan. 23 loss, Weber made the lineup and leadership changes. Tyler Griffey took Davis’ place in the starting lineup at Penn State, even though Davis played 27 minutes to Griffey’s 10, and Bill Cole was chosen as a captain with McCamey. We’ll have to wait until Illini picks on someone their own size, but — related or not — Weber’s changes after the Northwestern game have coincided with a distinct improvement in 2-point defense.

Illinois’ 2-point defense in Big Ten play:

The obvious caveat is the opposition. Illinois played the league’s three worst teams over its last three games. Iowa, Penn State and Indiana rank eighth, 10th and 11th respectively in 2-point shooting. At the same time, Northwestern is ninth, and the Wildcats torched Illinois inside in Evanston.

For a more apples-to-apples comparison, let’s look at Illinois’ 2-point defense in its first meeting against the bottom three compared to its second.

That’s a less jarring if still significant improvement, a difference of more than four points in a typical game. If Illinois can translate these performances into the very difficult matchups that lie ahead, perhaps the Illini can get the four wins they need to enter the Big Ten Tournament with a real shot at the NCAA Tournament. We should know all we need to know by the night of Feb. 20. Between now and then, Illinois travels to Wisconsin and Purdue, and the Illini also host Michigan State and Ohio State.

The preparatory season is over, and the heart of the Big Ten season now begins. Will this team in the “year between” rally for an unlikely run to the NCAA Tournament, or will it be a bleak March of looking ahead for Illini fans? We’ll begin to get answers on Saturday in Champaign.