Red arrows do not send central defenders charging at goal. It's a little difficult to explain.

Imagine you are Arsenal and you are facing West Brom. West Brom will have all defenders and midfielders and striker in their own half sitting back and tightening up when off the ball so that would make it more difficult to break down. Now say you have a left back moving up to a wide wing back position and a right back between central defenders and right midfielder waiting in space to receive the ball. Blue arrows (down) on your CBs will have them solely focus on defence. They won't look for space or an opportunity, just sit deep to avoid counters.

Now imagine 1 CB has a red arrow (up) he'll come forward most likely standing in line with opposition striker and play a pass to a player in space. A lot of defenders do this in real life when there are just not enough midfielders deep enough to orchestrate an attack. There is a slight risk of being countered but I think they help keep possession more and help pressing opponent.