The deal
Bulls get: Forward Noah Vonleh, cash considerations
Trail Blazers get: Rights to Milovan Rakovic
Get more trade grades for every deadline deal here
Portland Trail Blazers: A

Barring the Blazers making a bigger move to shed salary, dealing Vonleh was the logical way for them to duck the luxury tax. Having traded Allen Crabbe last summer, Portland managed to go from a potentially huge tax bill to avoiding the tax altogether without having to give up anything but cash considerations.
Because he's in the last year of his contract, trading Vonleh won't help the Blazers with their future tax crunch. They also won't likely miss him.
Through the course of his two-plus years in Portland, Vonleh showed flashes of making good on the potential that led the Charlotte Hornets to draft him No. 9 overall in 2014. However, he never was effective enough on a consistent basis to establish himself as part of the Blazers' future. Rookie Zach Collins took Vonleh's rotation spot this season, and Vonleh had played just 56 minutes since Dec. 16.
Chicago Bulls: B

The Bulls will get a look at Vonleh the remainder of the season and have the option to make him a restricted free agent by tendering a qualifying offer. Amazingly, after playing one year at Indiana and four in the NBA, Vonleh is still just 22.
If he's going to make it, Vonleh will have to become a more efficient scorer. This year's career-high .543 true shooting percentage is still worse than league average (.556), and that's despite Vonleh playing a tiny role in the Portland offense. He'd used just 11.6 percent of the team's plays while on the court. Barring unlikely improvement as a finisher, Vonleh may have to add 3-point range to develop into a rotation player.
While Chicago didn't get any draft value for taking on Vonleh's salary, doing so will save the team money. The remaining portion of Vonleh's contract will help the Bulls get closer to the NBA salary minimum, plus they pocket the cash received from the Blazers.