PG and the pacers are much better than the bulls roster. Turner > Lopez (by a fair amount), Young > Mirotic, Teague > Rondo/Grant. Maybe the only advantage the bulls have is Wade, but Wade was really bad for the bulls last season when he played.
Further Butler is #3 in WS (ahead of Leonard, James, Westbrook, and Curry), 10th in Box plus minus (9th is Curry), 12th in OBPM (1 spot ahead of Durant), 5th in VORP (ahead of curry, Leonard, CP3), 3rd in offensive win shares (only behind thomas and Harden), 11th in offensive rating (ahead of Thomas, Lebron, Leonard, etc.), 13th in PER, (ahead of Curry and John Wall), he is 3rd in WINS (behind lebron and curry), and 7th in RPM. The dude is also 27, on a two year contract, has the second highest PER in the final 5 minutes of games, and is making 19 million next season. To put that in perspective Allan Crabbe will be making the same salary next season. Butler is better than what Deron Williams and Carmelo Anthony were during their primes (going by advanced stats), yet got a worse return, while also stating he wanted to stay. The return the bulls got is historically bad by nearly every measure.