The word "composition" hints to me that it's Favors as he is a huge piece of the current 2-traditional big roster composition. I could also see Joe Johnson being in the deal too as it would explain why Jonas Jerebko would want to sign here. If Favors and Joe Johnson are both on the roster, Jerebko has 0 available minutes when both those dudes are healthy.
Yeah sounds like it's a hint toward Favors. I don't think the Jazz are wanting to trade Joe. I think Jerebko would get minutes if Favors and Joe were healthy though. Favors would get some of his minutes splitting time with Gobert at Center which would open some minutes at PF. And Joe will probably be on limited minutes for the regular season again. Plus he can get some of his minutes at 3.