(John McDonnell/The Washington Post)

Doug Fister will finally make his Nationals debut. In addition to giving Washington a reliable starter every fifth day, Fister also gives the Nats a sinker-ball (also referred to as a two-seam fastball) pitcher who can induce ground balls, when they do make contact (30.4 percent of the time it is thrown for a strike).

Source: Pitchergifs.com

Fister has seen a 74 percent increase in his ground balls per ball in play on his sinker since 2009. In 2013, hitters had an isolated power (the difference between a player’s slugging percentage and batting average, which illustrates how good a player is at hitting for extra bases) of just 0.087. Basically, the equivalent of Atlanta second baseman Dan Uggla (19 for 103 with two doubles and two home runs in 112 plate appearances).

He will rely on it less and less as the innings go on, but he will throw it as the first pitch to all batters a large portion of the time (57 percent to righties, 50 percent to lefties).

Matchup to watch against Oakland:

Fister has faced Josh Donaldson just a few times, but has given him a steady diet of sinkers on the inside part of the plate. Donaldson has managed to put them in play but has just one extra-base hit to show for it: a double to centerfield on a 1-0 count.