Johnson has quietly been one of the best pitchers in the National League since the beginning of the 2009 season. (I say "quietly" because nearly everything the Marlins do, short of winning a World Series, flies under the national media radar; obviously, fantasy owners and baseball fans are very much aware of him.) This year, he has 18 strikeouts and a 1.35 ERA in his first 20 innings pitched. Last year, he struck out over a batter an inning. Look for a Pirates lineup that has been very strikeout-prone so far to struggle against him and his nasty slider.
Paul Maholm has a 2.33 ERA so far this year, but he hasn't been nearly as impressive as that number indicates - his velocity is down a bit from years past.