Cruz's attacks on Trump will be analyzed by Hillary and the best of them will be used in the general election. Now that there is no way for Cruz to win he should stop attacking Trump, drop out and endorse Trump. Or at least shut up.
I haven't seen anything in the Cruz attacks on Trump that looked effective. Those "attacks" have been weak and almost irrelevant. If copying Cruz is the best Hillary and her minions can do, Trump will be in good shape. I agree though that Trump and Cruz, and their supporters, should stop attacking each other.