Bronco's success vs lack of was almost solely contingent on QB health.  We had 2 elite level QBs in his MWC year who outside of one game basically had a 5 year run of health.

Than came the Riley/Heaps era and we even managed to finish top 25 one year with a healthy Riley

If Taysom had the health of Hall, you would have had 2 more ranked season as an INDY. And if Beck or Hall had been injured in Bronco's MWC run there's absolutely no way any of those 4 teams finish the season ranked.

This isn't an argument pro/con Indy vs MWC, but just factually stating why Bronco was ranked more often in the MWC than he was as an INDY coach. Keep QB1 healthly in his tenure and more often than not, it meant a really good year.