Actually Bass is a better more versatile PF than Thompson overall because he's better defensively & as a scorer/free throw shooter. His numbers are only down because he's playing for the shytty Lakers with limited minutes.
Williams is streaky, but is still probably one of the best bench players in the game currently & is the extra offensive punch the Cavs need against more dominate offensive teams.
Dellavedova certainly isn't the best shooter in the world but he has improved 8.3 ppg (2015-2016) vs 4.8 ppg (2014-2015) & his defensive is stellar so he's pretty good as a 3rd backup PG.
Bass too small. Cavs don't need another Haslem.