Favs is glacially slow around the perimeter.
Jae isn't anything special by any means. He's just average at doing the things a 4 next to Gobert needs to do, which is much better than Favs is at doing the things a 4 next to Gobert needs to do. Favs isn't bad, he just isn't as good as Gobert and is really poor playing next to him.
Jae can also carry usage, which is something the starting lineup desperately needs. Gobert, Ingles, and Favors all cannot carry usage, which leads to Donovan having to carry too much and Rubio having to carry way, way too much. Ricky would be much better back in his Minnesota role with like 16 usage and 9 assists/game instead of 23 usage and 6 assists per game.