WASHINGTON --- The Bulls ruled September.

You remember. They had full participation at involuntary workouts. They passed conditioning tests and awarded Ryan Arcidiacono a wrestling-style championship belt when he won a draining and physical one-on-one tournament.

Vibes were high. Optimism reigned.

“Our goals for the season are to make the playoffs,” coach Jim Boylen said back on Sept. 30, the eve of training camp.

So what happened? How did the Bulls crash and burn their way to a 10-19 mark, coughing up a 26-point lead Monday night at Oklahoma City to further cement themselves as one of the league’s most underachieving teams?

Here are three culprits:

The coaching isn’t always transferring

In a Saturday interview, executive vice president John Paxson said he likes the teaching that he is seeing from Boylen and his staff but that what players absorb from practices and film sessions isn’t always taking hold in games. This can, in part, explain some of the Bulls’ fourth-quarter collapses.

After playing arguably their best first half of the season against the Thunder, the Bulls posted more turnovers than assists in the second half. More often than not, players stopped trusting the system and each other and the beautiful movement that defined the first half stagnated. Defensively, the Bulls failed to secure critical rebounds late and fouled at inopportune times.

There’s clearly a disconnect between what’s being taught and what’s playing out, especially when the same mistakes keep happening. Sure, that can be a byproduct of a young team, which the Bulls are. But it also calls into question how consistently Boylen and his staff’s message is getting through to players.

That’s why Paxson fielded a question on if he believes the players are still buying into what Boylen and his staff are selling.

Said Paxson: “The one thing I am confident is guys in that locker room share the same goal. They are together. There’s never going to be a perfect situation. There’s always some conflict. It can be teammate to teammate or coaches to players. That’s inevitable in this business. I don’t expect this group to fracture. I’d be disappointed if they did. All the guys in that locker room expressed to us their character and that’s not where they want to go or would ever go. I believe when they tell me that.

“I know that when things are bad or you’re not winning as much as you should, people want to point fingers. I’m not doing that internally. And we can’t do that internally. Once you do that, you’re in trouble.”

It’s true that the players work and genuinely like each other. The locker room is positive and professional. But the disconnect is real enough that players have subtly questioned an offensive system that has led to some overthinking over instinctual play and an aggressive defensive scheme that has produced turnovers but allowed open shots.

The offense isn’t producing

As of Tuesday morning, the Bulls’ offensive rating of 103.3 ranked 28th in the league.

Yes, the Bulls’ shot profile has looked solid for the most part, as Boylen likes to say. And, yes, they’ve missed open shots. They rank second in producing shots from 5 feet or less and take the 10th-most 3-pointers in the league but rank 29th and 22nd, respectively, in converting those opportunities.

It’s pretty hard to shoot 55.6 percent from 5 feet or less, but the Bulls are doing it. The middle-of-the-pack team, the 15th-place Nuggets, is converting 60.4 percent on such opportunities.

Still, what can’t be overlooked is individual player regression and stagnation at critical times. The Bulls shot 35.3 percent in the fourth quarter against the Thunder with two assists. They had almost as many turnovers with five as field goals with six. Nobody scored more than two points except Zach LaVine, who had 10. Chris Paul outscored the Bulls by himself.

Lauri Markkanen has showed flashes of turning the corner but then has a fourth quarter like he did against the Thunder---two points on two shots in close to 9 minutes.

Kris Dunn, who otherwise has had a brilliant bounce back season, is shooting 21 percent from 3-point range. Tomas Satoransky, while extremely solid overall, hasn’t completely solved the point guard issues because he’s not the type to break down defenses off the dribble.

Losing Otto Porter Jr. to a small fracture in his left foot has hurt, although Porter struggled initially this season before finally showing signs of life just before he got injured.

Paxson conceded a “miscalculation” on his part came from not realizing players would take so long to adjust to Boylen’s new offensive system, which was created with input from assistant coach Chris Fleming. In Paxson’s estimation, players aren’t playing instinctually enough.

Markkanen, in particular, has looked lost most often, a player whose first tendency isn’t to be aggressive and one who is begging to play with a true point guard.

The faster-paced system also relies on good decision-making from a team with a relatively low basketball IQ. Save for Satoransky and Ryan Arcidiacono, the latter a spot-minutes player, most rotation players’ assist-to-turnover ratios aren’t great.

Preseason concerns about physical play are being justified

On Media Day, Paxson noted how he’d be watching to see how a young, untested team handled physical play and adverse moments. On Saturday, Paxson acknowledged failure in those departments.

“Teams that are physical with us have hurt us a lot this year,” he said.

Opponents have outrebounded the Bulls in 20 of 29 games. Nine times, they have done so by double digits.

Too often, the Bulls lose battles for 50-50 balls. Worse, they consistently do so at critical times.

This dynamic is more subjective and based on the old-fashioned eye test, not analytics, but too often the Bulls succumb to adversity. A feeling of “here we go again” takes hold as a lead evaporates. This is played out by ball and player movement stagnating on the offensive end and poor rotations or boxouts transpiring at the defensive end.

The Bulls actually flipped this script in Monday’s collapse. After blowing all of their 26-point lead and falling behind by four with 76 seconds left, LaVine scored four straight points around a defensive stop to tie the game.

But multiple mistakes followed.

The problem with such underachieving is that it mostly obscures some legitimate positives. The defense is ranked ninth and sits second over the last 10 games. When he isn’t in foul trouble, Wendell Carter Jr. has become a consistent double-double threat. After an inefficient start, LaVine is putting up All-Star numbers.

The losing has prompted some moving of the goalposts. Boylen cites development and growth and how young the Bulls are often. And it’s true they are young.

But that’s not the message Boylen and management sent on the eve of training camp. In his Saturday interview, Paxson said the playoff talk was set publicly in part because of the vibe players gave following that triumphant September---when every team is undefeated.

And even with the slow start, Paxson didn’t back down from such talk.

“The way Jim is wired, we’re all wired, why shouldn’t we be sending the message to them to compete for the playoffs?” he said Saturday. “If that’s a pressure you put on people, I’m fine with that. I don’t waver.

“But I don’t know where that lands. I don’t know if that’s a realistic thing right now. We certainly haven’t played like a team that’s playoff-bound. But 50-some games left, it can change. If it doesn’t, we obviously didn’t achieve something that we thought we could’ve.”

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