[caption id="attachment_79160" align="alignright" width="300"] Vince Velasquez is entering his fourth season with the Phillies. (Ian D'Andrea)[/caption] As the Philadelphia Phillies enter a much anticipated 2019 campaign, much of the focus is on the offense and the significant upgrades made during the offseason. Having added Bryce Harper, J.T. Realmuto, Jean Segura and Andrew McCutchen, the Phillies seemingly have a lineup ready to compete for a World Series. The bullpen, with the offseason additions of David Robertson, Juan Nicasio and Jose Alvarez, looks strong on paper as well. So what could hold the Phillies back as they look to return to the postseason for first time since 2011? Perhaps the starting rotation, which returns a group where four-fifths of the team's starting pitchers posted ERAs north of five after the 2018 All-Star Break. Aaron Nola is a National League Cy Young Award contender. After him, there's not much certainty. Internally, there's hope from the Phillies that Nick Pivetta, who has flashed front-line potential, will step forward in 2019. 24-year-old Zach Eflin, once acquired in return for Jimmy Rollins, did go 7-2 with a 3.15 ERA in 2018, before a second-half collapse. Jake Arrieta's first two Spring Training starts have even given some hope that he'll have a bounce-back season following offseason surgery on a torn meniscus that he pitched through after the All-Star Break. And then there's Vince Velasquez, who figures to round out the starting rotation. Since he was acquired from the Houston Astros in the December 2015 Ken Giles trade, there's been buzz around Velasquez's top-of-the-rotation potential. At times, Velasquez has show signs of being a mid-to-front-end starter, but the biggest knock on him as been his perceived lack of secondary pitches. Coming into the 2019 season, the 26-year-old seems to be flying under-the-radar despite making much needed changes during the 2018 season. It is not news that Velasquez has a good fastball, and it is one that he had become quite reliant on during his time in Philadelphia. It is perfectly fine to throw a fastball with confidence like Velasquez, but his main issue early in his time with the Phillies was his inability to show consistent secondary pitches that kept hitters off balance. It appears that Velasquez made the much-needed change to his pitch distribution last season and it’s probably not a coincidence that it was his best as a major league pitcher. In previous seasons, Velasquez had never shown a secondary pitch more than 13 percent of the time. In 2018, however, he threw both his slider and curveball at a 15 percent clip. Of course, it's not as simple as just showing other pitches. Those pitches need to be effective. Starting with his slider, Velasquez increased his usage over seven percent between 2017 and 2018, but the biggest difference is that he used it far more when facing right-handed hitters. In 2017, Velasquez threw his slider 13.1 percent of the time to right-handed hitters. In 2018, that usage jumped to 24.5 percent. That is a significant change in use. In fact, Velasquez used his slider more in every scenario to right-handed hitters last season. The first pitch of the at-bat was typically a fastball for Velasquez in 2017, where he threw the pitch on 74 percent of right-handed at-bats and featured a slider just 11 percent of the time. In 2018, the fastball usage dropped to 60-percent while the slider was featured 24 percent of the time. When Velasquez was ahead in counts in 2018, he used the slider 26 percent of the time—up from 23 percent the prior year. While that is a slight uptick, the bigger usage increase came when Velasquez was in even counts and when behind. The ability to throw a true secondary pitch at any time is a weapon and Velasquez utilized that, throwing his slider in 28 percent of even counts and 21 percent when behind in the count. In the prior year, he used his slider in just 12 percent of even counts and just nine percent of the time when behind. The slider was one that Velasquez grew comfortable with given the increase in usage, but the results were there, too. In the 59 batted ball events that ended with a slider, Velasquez held opposing right-handed hitters to a .205 batting average and a .321 slugging percentage. One can now comfortably say that Velasquez has a true secondary to counter right-handed hitters with, as he not only generates good batted ball results, but has a very solid whiff rate on the pitch. These results were there in previous years as well, but it took time for him to use the pitch to his complete advantage. Here are the year-by-year usage and result numbers of Velasquez’s slider to right-handed hitters: Year Pitch # of pitches Usage BBE BA SLG WOBA XWOBA K% Whiff% 2018 Slider 310 24.5 59 0.205 0.321 0.257 0.288 22.6 34.8 2017 Slider 85 13.1 16 0.2 0.3 0.255 0.258 18.2 24.4 2016 Slider 147 13.1 22 0.276 0.379 0.306 0.263 25 31.3 The results of adding a slider as his secondary pitch helped Velasquez generate career-best results against right-handed hitters. If we look back at his 2017 results against same handed hitters, they hit him extremely well—posting an .824 OPS and .346 wOBA. Velasquez also allowed 10 of his 15 home runs to right-handed hitters in 2017. Last season, right-handed hitters fared far worse against Velasquez, posting a .606 OPS and .274 wOBA. Along with that, right-handed hitters managed just three home runs off Velasquez. The slider appears to be a true weapon for the 26-year-old, and one he should continue to use at a high rate in 2019. The other side of the equation for Vince Velasquez is figuring out how to handle left-handed hitters. In each of his three years in Philadelphia, left-handed hitters have caused fits for Velasquez, especially the last two seasons, where they posted an OPS of .879 and .889. The main offender in those two years has changed, though. In 2017, the problem Velasquez had was with his curveball—which he featured 12.6 percent of the time, while allowing a .412 batting average and a .529 slugging percentage. This past season, left-handed hitters managed a .290 batting average with a whopping .595 slugging percentage against the four-seam fastball. Going forward, this is going to be the area Velasquez needs to figure out to take the next step. The 2018 season was the third consecutive year Velasquez used his curveball more against left-handed hitters. While the results were not there in 2016 and 2017, the advanced data captured on them are close to his 2018 results. In 2016 and 2017, the expected slugging percentage (xSLG), was .295 and .318. While Velasquez actual numbers were far higher, these are close to the results witnessed in 2018 while throwing a curveball eight percent more. It is also important to note that in 2016 and 2017, Velasquez had just 36 batted ball events to left-handed hitters ending with a curveball—which is the same number he had in 2018. It will be important to monitor the use and results going forward, but the advanced numbers should make Velasquez confident in using his curveball going forward. The need for a true second pitch to left-handed hitters will be the next development for Velasquez. He has increased his sinker usage and thrown fewer changeups to left-handed hitters, but the results are similar with both pitches getting crushed. The changeup was the second-most featured pitch to left-handed hitters in 2017, but both expected and actual results were brutal. With the changeup getting hit hard, the change was made to an increase his sinker usage. That plan did not work either, as the sinker was tagged for a .373 batting average and .588 slugging percentage. The need for another pitch to neutralize left-handed bats is going to be important as teams work to gain advantages through splits. Growth is incredibly important, and Velasquez proved that he is working toward that in 2018. While not all the results were there, he did feature his slider to right-handed hitters more often and it paid serious dividends. On the other side of the plate, the on-field results weren’t as pretty, but the increased use of his curveball is a plus. This could be a pitch featured more-often to cut down on the sinkers and changeups that continue to trouble the 26-year-old. Velasquez had success with his fastball against left-handed hitters in the past, but he does need to find a pitch to slow down left-handed bats. 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