And for those who only read boxscores and don't watch games, the role of RJ and MW has been to stand on the 3-point line and be ready to catch-and-shoot, or drive on their man if they close out too hard, and they both run the floor. Because they are credible outside shooting threats (RJ: 43.8%, MW: 39.5%), this keeps the interior open for Favors (or Kanter) to post-up and play one-on-one, or have the space to run the pick-and-roll with the PG without running into a help defender.
Without credible outside shooters, we would be back to where we were 2 years ago, with defences playing "with one foot in the paint". The big men would face endless double-teams in the post and defenders would be free to help off their man whenever we tried to run a pick-and-roll.
Burks has made great strides in his game, but isn't yet the outside threat of RJ or MW. Having said that, he has played about the same minutes as RJ and more than MW this season, so the vets aren't actually holding him back. In fact, of the 'Core 5', only Kanter averages fewer minutes per game than RJ and MW, and that's attributable to his poor conditioning at the start of the season.
Also, the Core 5 are our top 5 in PPG, RJ and MW and 6th and 7th (which correlates with their lower usage rate). It's the Core 5 that are winning the games, RJ and MW are just providing depth. The vets are hardly "leading us to victory", its the youth getting the major minutes and doing most of the scoring. You want to win less, you have to bench the Core 5. You want to develop the Core 5, you have to play them and accept winning as a consequence.