Taking a look at 2017 on (the transition from the Butler to LaVine era), I think it really boils down to their inability to develop or sign a solid true point guard, and the one true point guard they signed since then has been injured pretty much his entire time on the Bulls. It's hard even looking back at the picks since then and thinking who they could've picked that would've made a difference outside the 2018 draft since most of the players picked around them weren't much better.
2017 - Markkanen - probably the right pick, better than the next 5 players drafted, but ended up trading for Derrick Jones and a lottery-protected pick that end up being protected
2018 - Carter Jr - a solid pick given the players drafted immediately above and below, but SGA or one of the Bridges would have been the right pick.
2018 - Chandler Hutchison - what was with their strange obsession with this guy? I remember everyone knew he was going to the Bulls. There was actually quite a bit of talent drafted after him (Mo Wagner, Shamet, Robert Williams, Brunson, Mitchell Robinson).
2019 - Coby White - they finally draft a "PG", but he averages less assists per game than Zion. I don't know who else they would have taken here that would be better though.
2020 - Patrick Williams - has never taken that next step, but still young and averages more PPG than the rest of the top 10 after him that year. The obvious answer would have been Haliburton, but he was picked 8 picks later.
2022 - Dalen Terry - not looking so good here, but wasn't a lottery pick
I think development is also a concern. Lauri, Wendell, Coby, and Patrick all seem/seemed to have hit a peak in year 3/4 and not take it to the next step. Lauri and Wendell both broke out after being traded, so it makes me wonder if Coby or Patrick would take off in another system.