Is this blogger's summary of Kovac's book accurate (http://blog.themistrading.com/2014/12/flash-war/)? Seems like the book refutes the accusation of HFT front-running but:
"Kovac then writes, “In other words, this research, cited by Lewis himself near the conclusion of his book, contradicts everything he has said about front-running in the prior two hundred pages.” Kovac suggests this is some kind of “Aha!” moment. See, he seems to say, there’s no front-running and Lewis’s own sources say so.
Your guess is as good as mine on this, but Kovac seems to be the one who apparently didn’t read the research. Go to the next paragraph in Clark-Joseph’s paper: “[T]he private information about price-impact generated by an HFT’s small aggressive orders enables that HFT to trade ahead of predictable demand [that is, front-run demand] at only those times when it is profitable to do so (i.e., when price-impact is large).”"