Line subs. why not?

Most teams change out the d linemen from time to time for a breather. Why not off. linemen. I would like to see Holland in for a series very now and then. Seems it would be good to see them in game situations. Also would have liked to have seen Clark stay in when the game was not in doubt.
But 6-2 is not bad the way coach is using his players.
Reg