I was at a feed seminar a number of years ago and this is the best explanation I've come across.  This was mostly referring to Holsteins but I believe it holds true for all breeds.

"The higher the percentage of corn in the ration, the less benefit you will see from processing the corn."

Meaning: 

Steer stuffers - whole corn

High Forage TMR - grind it like hog feed

It's not a recommendation of stuffer or TMR, just advice on what to do with the corn in each situation.