I frankly think Burnham was much better than Young last year. I think he is a big loss. Keeley has not been as good as Burnham to this point in their respective careers.
Burnham probably was better than Young last year, especially once he got healthy in the second half of the season. But Young has more physical upside and is younger. The staff made their decision there, and Burnham then made a business decision for himself. That created a spot for Keeley, who also probably has more upside, though he hasn't reached it yet either.