Getting Fidgety with My Index Funds

I'm a passive, weekly set it and forget it investor, but I'm currently getting the itch the move my holdings from something completely passive VTSAX to something only slightly less passive like VDADX. My thought process is that a large cap, dividend heavy fund might be more inclined to better weather what I feel is a likely downturn in the next couple of years than the market as a whole.

Someone please talk me out of the slippery slope I'm staring down of 1. fricking with my investment strategy because of my uneducated opinion of what the market might do 2. for a fund that has been in existence for a length of time roughly equivalent to a medium stretch of celebrity rehab.