That pulling is from heat. Just because the HAZ is small, it still causes the metal to shrink as it cools. That happens anytime you bring the metal up to melting temperature. By brazing you never get the metal to melting temp so you don't get that type of distortion. (You get a different type instead ) But it is a lot easier to deal with. I hear that a lot of new cars require MIG brazing for repairs so as not to upset the heat treated high strength steels they are made from. Auto body welding is an art unto itself. All I can say is practice on scrap and try different techniques to learn what does what. TIG brazing can be very gentle as long as you remember you are not looking to melt the base metal.