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By the Numbers: Vince Velasquez

What can the data tell us about one of the Phillies’ streakiest pitchers?

Ross D. Franklin/AP

Welcome to the first installment of By the Numbers, where I will be taking an analytic deep-dive into the data of various Phillies. In doing so, I will hopefully answer questions on why the player in question is performing the way he is.

First up is RHP Vince Velasquez. Velasquez arrived in Philadelphia in 2016 as a promising young pitcher who was recently acquired in the Ken Giles trade. Since then, he has struggled to stay afloat in the rotation after a few fledgling seasons. Those struggles reached their peak in 2019.

So, why did Velasquez have so many issues last season? The data should clear things up.

Here’s VV’s basic stat line from 2019:

Gabe Kapler began to use Velasquez as more of a swing-man last season, rather than a traditional starter, which is evidenced by his 10 relief appearances. The numbers above are mostly below average across the board, aside from his K% which is a few points above average. The most interesting stat to note is Velasquez’s HR rate of 5%. The league average amount for HR/PA is 3.6%. Among pitchers with at least 2000 total pitches last season, only three (Drew Smyly, Adrian Sampson, Caleb Smith) had higher home run rates than Velasquez. For reference, the three qualified pitchers with the lowest home run rates were Charlie Morton, Mike Soroka and Mike Clevinger.

Pitch Usage

It’s no secret Vince Velasquez gives up his fair share of hard contact, but not all hard hits are created equal. Let’s take a look at Velasquez’s pitch breakdown:

From this chart, we see that Velasquez is extremely fastball reliant. An 8% jump in four seam usage led to a sizable increase in VV’s fastball xwOBA in 2019. If you are unfamiliar with xwOBA, you can read more about it here.

xwOBA is a solid indicator of a pitcher’s overall contact-dependent performance, and this is breaking VV’s production down by pitch type. Another issue for Velasquez came from his slider getting hit considerably harder in 2019 than it did in 2018. His sinker also continued to struggle, although it was a low volume pitch.

The silver lining for Velasquez is his improving curveball, which is something to pay attention to as he continues to refine his arsenal. Also, the redevelopment of a changeup, something Velasquez and Bryan Price have reportedly been working on, could aid in a return to form moving forward.

Going back to his fastball, a 62.5% usage is exceptionally high for any pitch. Here are all the qualified pitchers whose average fastball velocities are within .5 MPH of Velasquez, sorted by usage:

Even pitchers with notoriously good fastballs (Scherzer, Verlander, Strasburg) are not throwing that pitch nearly as much as Velasquez.

Among qualified pitchers who throw their fastballs at least 15% of the time, here are the best ones from last season, measured by xwOBA:

Unsurprisingly, Gerrit Cole’s fastball is in a league of its own. One statistical comparison for VV is Chris Paddack, who also throws his fastball above 60%. Paddack’s 2019 four seam xwOBA of .285 was one of the best in the league, although it is likely that he will begin to throw his fastball less and less as his career progresses.

Fastball Performance

Because Velasquez is so dependent on his four seam fastball, taking a deeper look at the pitch is necessary in identifying his issues. I am only closely examining Velasquez’s fastball, not the rest of his arsenal, because it is far-and-away his most important pitch in terms of usage.

Here is the inning-by-inning breakdown of Velasquez’s fastball performance in 2019:

VV’s fastball velocity appears to hold up across the duration of the game, which is a positive. While its xwOBA is solid in the first four innings, his fastball starts to get knocked around at a much higher rate starting in the 5th.

It is also important to take note of Velasquez’s BABIP by inning. Lower BABIPs (below .300) sometimes mean the pitcher is getting lucky as balls in play are just not falling for hits. Velasquez’s 3rd inning BABIP of .143 is quite concerning. Pitchers can have lower BABIPs if they induce softer contact, but .143 almost certainly means batters are simply getting unlucky and hitting right into the defense against Velasquez.

His fastball performance in the 4th inning is very interesting. Velasquez’s strikeout rate is very high and he rarely walks batters with his fastball. However, his HR and barrel rates are both extremely high. 14.9% of VV’s plate appearances in the 4th inning result in a barrel, making his fastball almost unusable in that state. While his barrel rate decreases over the next few innings, it is still well above average.

This indicates Velasquez’s fastball is a high risk/high reward pitch. In many instances, he either makes a hitter miss with it, or it gets crushed.

Why does Velasquez’s fastball get hit as hard as it does? One issue could be the pitch’s spin efficiency. Spin efficiency measures how much of a pitch’s spin contributes to its movement. In today’s analytic environment, many pitchers are striving for maximum (near 100%) spin efficiency on their fastballs.

Vince Velasquez’s fastball spin efficiency is 79.2%, which ranks 485th in baseball.

Spin efficiency is a complicated concept, and it is not always the case that a pitcher wants maximum efficiency. However, holding all other things equal, here is a look at what improved spin efficiency can do for a fastball:

As you can see, the pitch with 40% spin efficiency is sort of lifeless, where as the pitch with 100% spin efficiency stays up coming out of the hand, giving it the appearance of rise. This contributes to pitcher deception, and it is why Gerrit Cole’s pitch overlay looks like this:

For reference, Gerrit Cole’s average spin efficiency on his fastball in 2019 was 97.1%. Any pitcher who can deceive hitters like this will be successful.

This VV overlay from just a few weeks ago shows promise that potential offseason fastball adjustments could be steering his deception in the right direction:

Zone/Split Breakdown

How Velasquez performs in different parts of the strike zone, as well as his L/R splits, can signal potential issues. Here is his total pitch breakdown and xwOBA by zone against righties in 2019:

Baseball Savant/

Velasquez’s pitch location profile primarily highlights the lower-half of the strike zone. He likes to work high/in and low/outside against right-handed hitters, in addition to favoring the lower part of the zone overall. Unless he hits his spot high/in, Velasquez gets hit hard almost everywhere on the inner half. While he also gets hit in the high/outside portion of the strike zone, working more outside than he currently does against righties could alleviate himself of some hard contact.

Here is VV’s zone success against lefties:

Baseball Savant/

Velasquez has considerably higher success staying outside against lefties versus pitching on the inner half. Much like he does against righties, VV also struggles down in the zone against lefties as well.

Against both lefties and righties, it would be beneficial for Velasquez to keep his fastball high in the zone. Regardless of potential fastball adjustments, Velasquez is a naturally high spin pitcher for his velocity, making him a candidate to run his four seam up in the zone and induce fly balls. Not all pitchers have to live low in the zone.

Batted Ball Profile

Here is Velasquez’s total batted ball profile, courtesy of BaseballSavant:

Baseball Savant/

This chart contains VV’s lone 2020 start up to this point. His ground ball rate has been decreasing considerably, which could explain his increased barrel numbers. While it could play to Velasquez’s advantage to be a fly ball pitcher, I do not believe it was his intention to induce ground balls at almost 9% below the league average last season.

Comparing this to the zone breakdown, it would appear Velasquez’s biggest fault is leaving pitches low in the zone that result in hard contact, rather than ground balls.

Plate Discipline

Most of Velasquez’s advanced plate discipline statistics from last season were league average. However, there are some cherry-picked metrics that could provide context.

Velasquez’s zone swing rate was almost 6% above league average last season, meaning he was likely leaving the ball over the plate too much and hitters were taking advantage. His chase contact percentage, while around league average, was up almost 5% from the previous season. This indicates that hitters were having more success making contact against pitches outside of the strike zone, which could be a contributing factor in VV’s hard contact issues.

Altogether, this means Velasquez’s struggles may be stemming from missing his spots as well as simply getting hit hard in various parts of the zone.


In short, Vince Velasquez’s fastball holds the key to his future success. Even if he refines that pitch, along with the rest of his arsenal, throwing it marginally less could pay dividends. The rest of his repertoire is inconsistent but has shown promise in certain parts of the last 2 seasons.

Regardless, if he does refine his fastball it could result in softer contact moving forward. His tendency to stay low in the zone could also be contributing to his struggles.

With regards to his role, VV loses consistency after the 3rd inning, and it could be in his best interest to “open” games moving forward, rather than be a regular starter.

Whether it’s making changes to his fastball or altering where he throws in the zone or finding more consistency in the later innings, if Velasquez cannot shake the high exit velocities, then he will not last much longer in the rotation.

Thus far in 2020, Velasquez has switched things up a bit and appears to sport a slightly different repertoire. While he was knocked around in his first start, the jury is still out on whether or not the changes will have a positive effect moving forward.