Being a huge fan since day 1, this is a little hard to say. But, I am getting really tired of Barry's "no kill" speech! There is NOT "always another way" as Flash loves to say, over and over.
Perhaps if he had to visit the families of everyone that DeVoe has killed, so far, he might realize that the life of 1 murderer is worth far less than the lives of dozens of innocents.
Also, he should hold himself PERSONALLY responsible for any future deaths committed by Team DeVoe.
Then again, he has already proven how self righteous he is, by his Flashpoint blunders!