Why my team beats this other team would be a fun exercise... I'm ready to embrace total intellectual dishonesty in defense of my squad.
Toward this end... I officially throw down my gauntlet. Any GM can issue me a challenge by writing why your team beats mine, and I'll respond in kind.
Bulls v Celtics
Starters:
PG: Chauncey v Steph
SG: Kobe v. Jrue
SF: Jimmy v Hedo
PF: Al v Giannis
C: Yao v Porzingis
Bench
PG: D-Will v Brunson
SG: Eric Gordon v Dipo
SF: Granger v Amen Thompson
PF: Zion v Brand
C: Pau v DeAndre Jordan
Offensively I concede a spacing advantage to the Celts. Lots of shooting to give Giannis a lot of room to attack either in iso or off 2-man actions. Plus Porzingis poses problems for Yao as a legit stretch big. But I think the Bulls would be capable of stifling even so potent an offense just as the 2009 Lakers muzzled the 4-out + Dwight Magic (holding them to 10 below their season offensive rating). Even with Rashard Lewis raining 3s on the Lakers twin towers, the Lakers dominated by shutting down Howard.
I think the Bulls pose a similar problem for Giannis - who would face one of his most daunting man defenders in Al plus the overwhelming size of Yao in the paint (or Pau off the bench). Further the speed, tenacity and defensive instincts of the Bulls perimeter trio would prey heavily on Giannis' drives and kickouts, turning him over heavily.
Steph of course poses another set of problems but the Bulls are well equipped here too. Use the Cavs strategy of beating him up on both ends which Billups/Kobe/Butler group do exceptionally well (and beefy bench guards D-Will and Gordon can also do). As for the Jrue/Hedo/Porzingis trio, the Bulls are happy to shift the offensive burden to them, trusting that they will not be able to outproduce their counterparts.
Offensively, the Bulls have numerous areas to feast. While Jrue/Giannis can cover a lot of ground, the C's are vulnerable in several areas. Curry has to deal with prime Billups - a physical load for any slight PG - and would suffer very badly in any switch. Hedo is very poorly equipped to handle Jimmy Butler. And both Giannis and Porzingis would struggle mightily with Yao. They can try packing the paint, but the skill level of the big men and the proficiency of the entire team from mid-range means it won't be enough.
Off the bench, the Bulls enjoy a tremendous advantage in firepower. Every single Bulls bench player is a bonafide 20+ppg threat that operates from different parts of the floor. The C's on the other hand struggle with spacing issues with the Amen/Brand/DAJ frontcourt allowing the Bulls to key in their perimeter duo. I trust D-Will to exploit his own mismatch and get Zion going against Brand as well.
I expect the C's to steal a game or 2 in a playoff series thanks to their shooting prowess but to succumb to the Bulls onslaught of power, physicality, skill and size.