Well, lets look at it: to start, you laid the foundation well by stating - "We've played one of the toughest schedules in the nation so far...".
Against that schedule, we are #28 in Scoring Defense, #4 in FG % Defense, and #95 in 3-pt. FG % Defense. The latter stat needs improvement.
We are #1 in Blocked Shots per game, #11 in Defensive Rebounds per gm, #69 in steals per game, #166 in forced turnovers (7th in the SEC).
We do need to improve in the areas of 3-pt. FG % Defense, steals and forced turnovers. We are a guard-heavy team with Harris, Cooke, and Henderson, and all are very capable one-on-one defenders. I think the improved offense has been cause for the team getting lazy in certain defensive areas: we were doing much better in non-SEC play in steals, FG% D and 3-pt. FG % D, while scoring a bit less each game, and the non-SEC schedule was pretty decent. Since SEC play began, those numbers have all dipped somewhat, while the offense has exploded.
Against Ole Miss, our defense was purely suffocating in the 1st half, holding them to only 2 pts, while our own scoring was down quite a bit. In the 2nd half, we turned the offense way up, and scored 55 pts after halftime, but the Rebels also got their own offense un-tracked, and had a decent half against us.
We also need to remember that we've played Baylor, Arkansas, Miss State, Maryland, even South Dakota. That's 5 of the current top 10 in the nation in Scoring Offense. Some defensive stats are not that good - and really, the steals/gm and 3-pt. FG % D are decent, to be honest - while others are nationally elite. Against some of the elite offenses in the nation, that's not too bad....