The Warriors are perhaps the most famous example of a team playing small-ball could win an NBA title, and they came four bad minutes from winning two in a row. Now with the addition of Kevin Durant, the Warriors potentially have an 'Ultra' Death Lineup in Curry-Thompson-Iguodala-Durant-Green. It's scary just talking about it, but the underlying theme is that small-ball is the new movement in the NBA.
The Bulls will likely be steering into the movement of trying to play small as well. Joakim Noah and Pau Gasol are gone. Fred Hoiberg is known for his offense, and the Bulls will likely be stronger on that end than the defensive one. But they have to develop a good small ball lineup.
They tried to play small ball last year but it wasn't that successful. Part of the reason why the Bulls don't have a pure stretch four that is consistent enough. Nikola Mirotic is perfect for that role, but there was injury, his lack of defense, and inconsistent shooting almost made him unplayable sometimes but saw a strong finish to the season.
The Bulls also tried to play Doug McDermott there. It was done more in the Summer League and in the preseason but not a lot when the games mattered. And the word out of this year's Summer League is the Bulls will probably try to do that this year as well.
With Denzel Valentine coming in, McDermott is going to have to compete with another small forward for minutes. Even with the arrival of Robin Lopez, the minutes could still be open due to the rumblings that Taj Gibson could be moved before the season starts. That could open up to the door to McDermott. But it would not be smart to try this idea again.
It's no secret that Doug McDermott has trouble on the defensive end. His lack of foot speed makes him a horrible mismatch for any speedy wing when it comes to Doug trying to stay in front of them. But he is 6'8 and could matchup against a big power forward.
The problem is he is a really bad rebounder, much due to his lack of strength and awareness. McDermott averaged 3.8 rebounds per 36 minutes, one of the lowest season averages on the Bulls roster (it was a hair below Derrick Rose). Compare that Mirotic's per-36 rate of 7.9. Unless he gains some strength this offseason, McDermott will get eaten alive in the post against a big man and if the Bulls are matching small for small, he may be overwhelmed while dealing with a guy like Draymond Green, who is the extreme in this case, but there are others at the position who can simlarly shoot and put the ball on the floor.
The guy Chicago should continue playing at the four should be Nikola Mirotic. He was brought in and hailed as a big man who can stretch the floor and he has shown flashes of potential. We have seen games where Niko takes advantage of a PF who struggles on defense.
His ability to stretch the floor and knock down open shots is key for Chicago. Last year 56.8% of Mirotic's attempts came from beyond the three-point line and he was able to knock them down 39% of the time. Although his three-point percentage wasn't the highest on the Bulls, he took almost two more three's each game than the next guy on the list, which is McDermott. His three-point shooting improved from last year, including nearly a 12% jump in 3-point percentage on corner threes (regarded as the easiest spot on the three-point line to shoot from).
Niko needs to learn on how to create off the dribble as 94.8% of his three-point field goals were assisted. With that being said, he still brings a solid shooting presence and his size makes him the better stretch four for the Bulls.
But there is still hope for McDermott, If he bulks up this summer and gets stronger. Stephen Noh of the Athletic explained it in his article about McDermott (I suggest you check it out, it's very good) :
McDermott simply cannot afford to play at a strength disadvantage on defense because he is already giving up so much in terms of athleticism. At 6-foot-8, he has decent height. But he has a very short wingspan, a low vertical and lacks speed. His lack of physical tools are why he’s already the worst player in NBA history at accruing blocks and steals.
His lack of athleticism can be hidden against certain types of power forwards. If he can bulk up and rebound the ball, the Bulls can at least have some more options on where to hide him defensively.
But right now, you can't see that. Outside of Mirotic, you could probably put Jimmy Butler at the four before you would with McDermott. McDermott at the four sounds like a very enticing idea considering how the league is shifting to "small-ball", but as of right now, it should be avoided.