Luke Gregerson is a fascinating player who has proven major league pitchers can be successful with odd and unusual repertoires. Throughout his career, Gregerson has found success using his terrific slider most of the time while mixing in a soft fastball just enough to keep hitters honest.Few pitchers, especially late-inning relievers, employ an arsenal similar to the soft-tossing righty, and those who do are typically specialists who are only effective against same-side hitters. Gregerson is not a specialist, however, he is the closer on the American League West-leading Astros and a big part of their surprising playoff run. MORE: Astros could prove to be formidable in OctoberThe book on Gregerson has always b
een to expect the slider at almost all times, which until this year was justified by the righty using it 46 percent of the time against left-handed hitters and an astounding 64 percent of the time against right-handed hitters. He has been a bit of a one trick pony, but that trick was good enough for him to thrive as a setup man for the Padres and Athletics and earn a handsome three-year, $18.5 million deal with the Astros last offseason. Gregerson is no longer a one trick pony. The book has changed. His slider is still devastating, but hitters sitting on the slider every pitch are very likely to walk back to the dugout shaking their heads.A New ApproachThis season, Gregerson has increased his fastball usage by a substantial 14 percent. Despite having a career fastball usage of just 41 percent and a 2014 figure of just 45 percent, he has increased his usage to a resounding career high of 60 percent.Gregerson’s heater is technically classified as a sinker, save for the odd three percent classified as a four-seam fastball. The sinker is typically thrown down and away from both right-handed and left-handed hitters and is instrumental in his ability to generate ground balls at a stellar 60 percent clip. The sinker itself is put on the ground 15 percent of the time it is thrown, a terrific mark and far above the 7.5 percent rate for the slider.The slider, meanwhile, remains his strikeout pitch with a stellar 22.5 percent whiff rate, compared to the relatively meager ten percent mark of the sinker. The pitches play nicely off of each other and allow Gregerson to maintain both a quality 22.8 strikeout percentage and a high ground ball rate.The usage of the pitches varies greatly depending on the handedness of the opposing hitter. Against left-handed hitters, Gregerson increases his usage of the sinker to a robust 72 percent and using the slider just 22 percent of the time. As a first pitch, the slider is shelved even more, as 92 percent of his first pitches are sinkers. I find it difficult to believe that any pitcher can get away with such a predictable first pitch for very long. It would be very easy for opposing batters to sit on the sinker early when they know it is almost definitely coming. On the other hand, Gregerson commands his sinker very well and gets lots of ground balls with the pitch, so it seems reasonable for an opposing hitter to let the well-located sinker down and away go by, even if it is in the strike zone. With two strikes, the slider becomes the most frequent pitch selection, a relatively light 54 percent. This usage pattern against lefties shows that Gregerson is understandably wary of throwing too many sliders against lefties. With the pitch breaking in towards a lefty, it is a bit easier to track than the pitch moving away from a righty.Against right-handed hitters, the script is flipped. The slider becomes the most prominent pitch, checking in at 57 percent usage while the sinker sits at just 40 percent. Those rates are nearly the same for first pitches, making it much more difficult for opposing hitters to successfully guess what pitch is coming. The slider is also used heavily at 74 percent with two strikes, which makes sense given the high whiff rate with the pitch.The ResultsSinker-slider pitchers generally succeed by throwing both pitches low in the zone, utilizing the downward movement to groundballs, and mixing the pitches just enough to keep hitters guessing. Gregerson does some of this sometimes, specifically getting ground balls by throwing sinkers down in the zone to lefties. But he also can be predictable, especially against lefties early in the count. Finally, Gregerson strikes out substantially more hitters than most sinker-slider pitchers.The results are difficult to argue with. In spite of the predictability early in counts against opposite-handed hitters, Gregerson has held lefties to a .259 wOBA this season. It’s difficult to draw conclusions from relief pitcher single season splits, but his effectiveness against lefties is also supported by his .231 wOBA against in 2014.The success against opposite-handed hitters, buoyed by his increased fastball rate against them, is one of the biggest reasons why Gregerson has thrived in Houston. His 2.88 ERA is slightly up, but the ground ball rate is way up for the second straight season, the walks have dropped again to just 5.1 percent, and the strikeouts are up to 22.8 percent this season. Furthermore, his soft contact rate has increased to 24.6 percent, at the expense of the hard contact and medium contact rates. The underlying skills have all increased, so even though Gregerson’s ERA sits over 0.7 runs higher than his 2014 luck-aided figure (his xFIP was 3.29 – over a run higher than his 2.12 ERA last season), we are seeing a better pitcher this season.The sinker has helped Gregerson generate more ground balls while not compromising his strikeout rate, a terrific combination for any pitcher. The slider is still a tremendous weapon and essential to his approach against righties, but he has found another way to find success. It will be extremely interesting to see if he can continue to throw such high rates of sinkers to lefties on the first pitch, or if opposing hitters will adjust, forcing Gregerson to rethink his sequencing. For now, however, the high rate of sinkers is working effectively, and allowing him to enjoy his first full season as a closer on one of the American League’s most exciting teams.Sporting News contributor Dan Weigel pitched for Bucknell University and is a player and a coach for national and club youth teams in the United Kingdom. Follow him on Twitter: @danweigel38 .