depends on your perspective. when you have a guy who had his best statistical season, 2nd in MVP and was top 5 in jersey sales. it makes all kinds of finanical sense to resign him and cash in. (this is not advocating he is good or not, just that look at it from finanical perspective).
if you are actually looking at football stuff, then yeah, its stupid. Jerry cornered himself with Dak and the rest of the QBs on the roster. he got caught being stupid trading for Lance, where rumors were nobody really wanted him. then he hasn't drafted a QB in what? like 5,6, years (I don't count 6th, 7th round picks nothing but tokens, you must invest in some talent to develop, not long shots).
you have to remember, winning championships is not the top priority in dallas. when you fully grasp that and put all football stuff in the back burner, then all the moves make sense.