Why did it take mcvay so long to realize he needed to switch up personel.

What bugs me about mcvay is that he doesn't adjust well. When things are working well in the first half we succeed, but when they are not he can't adjust and try new things. We have all been calling for mcvay to switch up the offense and run some different personnel and he figures the perfect time to run this is against the lowly jaguars? Where was this grouping for the Superbowl, or when we were struggling early this year and we had a bye week to install new packages?