The Bucks defense has been terrible all season long. According to defensive rating, the Bucks have the league's third worst defense, giving up 106.4 points per 100 possessions. There has been little discernible difference between their defense from game-to-game and startlingly little fluctuation from month-to-month. While many (yours truly included) thought the Bucks would improve on defense as the season progressed with newcomers becoming more comfortable with the Bucks' aggressive system, there has been little improvement and now the initial problems have manifested themselves into a brand new problem for the team. Two of the Bucks season-long problems converged with a new problem perfectly on a single play last Tuesday against the Orlando Magic:
Let's start at the moment things begin to go wrong with Victor Oladipo catching the ball on the left wing covered by Jabari Parker. Parker has struggled mightily on the defensive end during his NBA career, but those struggles are not unexpected. Throughout the draft process, many questioned Parker's ability to play defense in the NBA and noted the likelihood that he would be a below average defender at the start of his career.
As noted by Vantage Sports, Parker has really struggled to keep his assignment in front of him on defense. On the season, Parker's Keep-in-Front percentage is 53.5%, which is about two percent higher than the league average for small forwards, but nowhere near the league average (70.1%) for power forwards. Obviously, this number needs to be taken with a large grain of salt as Parker has covered multiple positions, and even gone as far as asking for the toughest assignments on given nights. Even with those qualifiers being noted, Parker has noticeably struggled to keep offensive players in front of him off the dribble and can pretty clearly be seen as the weakest defender among the Bucks' "preferred" starters.
(Aside: Carter-Williams, Middleton, and Antetokounmpo are all nearly exactly average in this regard at point guard, shooting guard, and small forward respectively. It should be noted that Antetokounmpo's number could be artificially inflated by covering power forwards from time-to-time. Monroe is below average, as noted in the Vantage Sports piece, but not nearly to the extent of Parker.)
In the play above though, Oladipo does not blow by Parker. Instead, Parker does a relatively good job staying connected on Oladipo's left hip and offers a fair amount of resistance, which may suggest he actually is improving on defense as Parker recently suggested. Remember, improvement from awful to slightly less awful is still improvement. So, though Parker has often struggled with his on-ball defense, he was more than enough of a hindrance to Oladipo for Bucks' defenders on the backside to help him out and shut down the drive.
(Note: Parker's responsibility may likely have been to force Oladipo to the baseline, which he failed to do. But again, slightly less awful!)
As Oladipo drives to the basket, Greg Monroe does his best to stay in the lane for 2.9 seconds and provide the help that Parker would need at the rim and does a pretty respectable job. It appears he is ready to step in and help out at a shot at the rim if Oladipo is able to get to the rim, but does not have to do it on the above play.
Though Monroe appears to be near the rim, his help has been significantly different than Zaza Pachulia's help last season. While there is no denying that Monroe is regularly in a position to contest shots at the rim, the best rim protectors can actively keep offensive players away from the rim in addition to protecting the rim.
Last season, Pachulia was fantastic at deterring opponents from actually taking shots at the rim with opponents taking 2.8 fewer shots at the rim per 36 minutes. Monroe has not been quite as good at that this season with teams taking just .8 fewer shots at the rim per 36 with Monroe on the floor. The major difference is the place where each player meets an attacking offensive player. Monroe is often much closer to the rim than Pachulia was in the same situations last season. There is rarely a time where opponents see Monroe's backside help and pass to a teammate or slow down, instead they actively attack Monroe. That is a problem, but again, on this play, it is not a problem. Monroe is in position and Oladipo passes out to Evan Fournier before Monroe even has a chance to challenge a shot at the rim.
Now, to the actual problem on this play, Khris Middleton. As suggested earlier, Middleton is fine, if unspectacular, in a one-on-one situation against shooting guards or small forwards leaguewide, but many likely remember the oft-cited defensive RPM statistic that measured Middleton as one of the league's ten most impactful defenders last season. While many think that number overrates Middleton's impact, it would be hard to deny Middleton's role in the swarming, aggressive defense the Bucks played last season.
On this play, Middleton's defense would not be described as aggressive or swarming. Instead, it would be described as useless. The Magic have struggled to find enough shooting to make their offense work this entire season, making multiple changes to their lineups to stagger enough shooting on the floor. Yet, on this play, Middleton finds himself covering the lone deadeye shooter on the floor and decides to linger in the middle of the floor in a position that neither actually helps Parker, denies Oladipo's passing line to Fournier, nor actually defends Fournier. It does absolutely nothing.
This play is emblematic of much of the Bucks' off-ball defense. Over and over, Bucks defenders stand around and look at opposing players penetrating to the basket without actually making a decision. Their help is neither aggressive enough to force a trap (and thus, force a series of rotations by teammates) or quick enough to actually recover to their assignments. Just watch a Bucks game for five minutes and you will be sickened by the number of times you see a defender sitting in help purgatory dooming the Bucks defense.
The problem seems simple to fix because all Jason Kidd should need to do is to tell players to stop over-helping and it should stop, but it's much more complex. NBA defense is built on trust. Teammates need to understand what their teammates are going to do and believe that their teammates can actually handle their responsibilities. That trust and belief started to disappear a few months ago and has essentially been nonexistent for the last month.
There aren't adjustments or tweaks that can be made to fix the Bucks' defense this season. The fundamental problems fostered an environment of distrust, which created even more problems. The defense is broken and, quite simply, there is no fixing the Bucks' defense this season.