Before I begin comparing the two pitchers, I must first state that "stuff" is one of the most difficult things to objectify when analyzing pitchers—largely because it is an inherently vague term. It is even harder to compare "stuff" among pitchers because some may rely on fastballs for success while others may rely on breaking balls and/or offspeed stuff. For clarity purposes, there are three components I primarily use when analyzing "stuff": 1) Movement (both horizontal and vertical), 2) Velocity, and 3) Versatility. Sure, results like batting average and slugging percentage matter, but I look at these secondarily, and as you will see toward the end of this post (when looking at Arsenal Scores), even these come after other results such as ground ball and whiff rates.
While I wrote ever fondly of Garcia's "stuff" in June of last season, I've always found myself siding with Martinez's, citing his electric velocity and arsenal versatility as the two biggest contributing factors behind this opinion. Thus, I was intrigued when Goold stated that Garcia had the better stuff, even after he used the "by a hair" qualifier in his response. Concerned that my support of Martinez was plagued by recency bias since Garcia missed the second half of last season, I turned to BrooksBaseball to evaluate the career average movements (horizontal and vertical) and velocities of the pitches thrown by Garcia and Martinez.
Dragless horizontal movement (inches)
Since Garcia is left-handed and Martinez is right-handed, one should look at the absolute values of these numbers when comparing between the two pitchers. However, when comparing internally (i.e. Martinez's sinker compared to his slider), keeping in mind the negative sign is a necessity. As a refresher, a negative value from a right-hander means arm-side movement, while a negative value from a left-hander means glove-side movement.
As you can see, it appears that Martinez has more horizontal movement than Garcia on all pitches but the changeup. Intrigued by the large variance in horizontal movement between each pitcher's fourseam fastball, I asked Harry Pavlidis what to make of it. He stated that arm slot (i.e. Garcia comes over the top a lot more on his fourseamer) plays a role, and to me, that made a whole lot of sense.
As I've stated in the past, I find more use in comparing horizontal movements of pitches internally, instead of between two pitchers. In an ideal world, a pitcher's changeup will track a similar path to that of his fastball—that’s just the point of the pitch. On the other hand, a breaking ball (particularly a more horizontal slider) will move in the opposite direction of a given pitcher's fastballs/changeup. That being said, the horizontal difference (23.47 inches) between Martinez's slider and sinker is borderline unfair to hitters. Because of this, I give the edge to Martinez when looking at horizontal movement.
Dragless vertical movement + gravity (inches)
To be honest, it's tough to determine a real "winner" for this section. Sure, Garcia's fourseamer drops more than Martinez's, but as discussed in the horizontal movement section, a big reason behind this is his over-the-top arm slot on the pitch. Each of the other pitches have a comparable amount of drop to them, with Martinez's slider having slightly more bite to it. While not very intuitive, the pitches you'd expect to drop more (i.e. changeup, breaking balls) do, in fact, have more negative vertical movement, so that is always a good thing.
Average velocity (MPH)
Martinez wins this section easily. A 96.44 MPH sinker with movement is not fair. The one interesting thing I did notice, however, is that Garcia's career average slider velocity is virtually identical to Martinez's, which is a really good thing for Garcia's effectiveness. Given that Garcia is healthy enough to pitch this season, I believe it is in his best interest to keep his slider velocity up (85 MPH or higher), as it dipped to 82.59 MPH in 2014 and lacked some of its usual luster/effectiveness.
While Garcia technically has one more pitch than Martinez, I still give the edge to Martinez here. Both of Martinez's fastballs have the ability to blow hitters away, and even if hitters do make contact, it is likely of the ground-ball variety. At present, Garcia's changeup is probably better than Martinez's, but El Gallo's is nothing to sneeze at, especially as the sample size grows. In short, having the threat of following a breaking ball or changeup with a near-100-MPH fastball just screams versatility to me.
Secondarily, a very brief look at some results
Enos Sarris and Daniel Schwartz are doing some fantastic pitching analysis over at Fangraphs, particularly regarding a statistic they call Arsenal Score (Schwartz's variation is called "Rep.Score"). The basic premise behind Arsenal Score is how often pitchers get ground balls and how often they get swinging strikes. I do not want to be a content vulture, so if this is something that interests you, please follow the links to Sarris' and Schwartz's articles below.
First, via Enos Sarris at Fangraphs:
Second, via Daniel Schwartz at Fangraphs:
As you can see, Martinez edges Garcia in both Arsenal Score and Rep.Score, but the fact that both find themselves in the league's top seven is especially promising. I look forward to an increased sample size (particularly with Martinez now slated as a starter) and the evolution of these two statistics.
One last results-related thing Pavlidis told me to look at was how each pitcher performed up in the zone. Based on BrookBaseball's ISO maps, Martinez has been significantly more effective than Garcia on pitches up in the zone. Given the sheer difference in pitch velocity between the two pitchers, this isn't necessarily unexpected, but it is always appreciated to have concrete data available to back up one's thoughts.
While both Garcia and Martinez have excellent "stuff," the slight edge goes to Martinez, and this gap may widen even further if Garcia's arsenal is limited in his return from yet another arm injury.
Credit to BrooksBaseball for the data used in this post. For those wondering, the horizontal and vertical movements found in the tables are an average of the players' entire career (i.e. Garcia: 2008-2014, Martinez: 2013-2014), instead of just one season. And yes, I used Excel this time around.