One of the biggest surprises of Thursday's NBA Draft wasn't a pick that was made during the event. Rather, the Chicago Bulls trading star forward Jimmy Butler to the Minnesota Timberwolves highlighted the night.

The Bulls got Kris Dunn, Zach LaVine and No. 7 overall pick Lauri Markkanen in return, but that didn't seem to be very much in exchange for one of the top-15 players in the league right now.

However, former Boston Celtic Antoine Walker thinks he knows why the Bulls were so eager to deal Butler, and said as much on Monday morning.

During his appearance on ESPN Radio, which you can see below, Walker said he believes Chicago dealt its star player for cheap because Butler is a divisive presence in the locker room:

“He’s just a bad locker room guy,” Walker said in the video. “A lot of outbursts took place throughout the season with the coaches and the players.

“When you’re trying to build something in Chicago and he’s your best player, he needs to be a leader, and he was a poor example, and that’s why I think the Bulls parted ways with him.”

Obviously, Walker's comments are strong ones and are likely the result of unnamed sources who want to hurt Butler's image as he heads out of Chicago. Without more substantial proof, it's hard to take Walker's reasoning as fact.

However, it's possible Butler was a bit upset this season, as the Bulls' offseason gambles to sign Dwyane Wade and Rajon Rondo didn't exactly pay off. Chicago had to fight until the very last day of the regular season just to earn the No. 8 seed in the Eastern Conference playoffs.

The Bulls have tried to put a positive spin on their decision to deal the star forward, despite many fans being angry with the way the trade went down. The Bulls' front office told ESPN.com that it's all part of a strategy to get younger across the board:

"What we've done tonight is set a direction," said John Paxson, the Bulls' vice president of basketball operations. "We're going to do it with young players. We're going to be disciplined and patient.

"These are hard things to do. We traded a guy we really like. Tonight, we made a decision to change direction and define our path."

Though LaVine is a rising star, he's no Butler, and many don't see Markkanen being good enough to replace Butler's production. Therefore, when the Bulls step on the court to start the 2017-18 season, they'll likely be a much worse team than they were last season.