Calling in stuff because you just missplayed is so rewarding for the other player who has to repair and then get's dived. (i hope i could bring over the sarcasm well!)
Tank Call ins have to be tied to tech and have to have a certain cost. "Battlegroups" like we had with Panthers in CoH1, or t34/85s and okw p4's should just outright be removed
Battlegroups are actually a nice way to balance stuff out. You cant stall for just one unit. You have to take everything, which takes more careful planning.
It will kill panic button call ins, since it will cost way more.