ViewRay reported Q2 results that beat sales expectations, though "poor" backlog growth and a pushout of five systems into 2020 will lead to weakness in the shares, Piper Jaffray analyst Matt O'Brien tells investors in a research note. While a "little disappointed" to see so few new systems in the order book, the analyst agrees with management that capital sales can be lumpy. He's "defending the name" amid today's selloff because he believes ViewRay's technology value is "significant." This "hiccup" in 2019 could be easily followed by many years of "top-tier growth" given the unique advantages of the MRIdian system, says O'Brien. He cut his price target for the shares to $6 from $15 but reiterates an Overweight rating on ViewRay.