The 2015 season has been pivotal and possibly career-defining for 23-year-old starting pitcher Carlos Martinez. Deservingly named to his first All-Star Game, it is safe to say Martinez has made the most of his first full stint in the starting rotation of the St. Louis Cardinals, and it is evident that he has no plans of permanently returning to the bullpen. Now, there still is a chance Martinez is sent to the bullpen for the playoffs, but given his regular season performance, this will be merely temporary.
Despite the transition to the rotation being relatively smooth thus far, it is not fair to say it came easily for Martinez as there were real concerns about whether or not he could truly "make it" as a starting pitcher. There were concerns about his durability and his ability to consistently pitch deep into ball games (i.e. six innings or more). There were concerns about his lack of success against left-handed hitters out of the bullpen. There were concerns about limited confidence and effectiveness in his secondary pitches. Well, up to this point, Martinez has successfully quashed each one of these concerns, and it all begins with one major adjustment: significant diversification of his pitch usage, as seen in the graph below:
Diversification of pitch usage
The gap between his fourseamer usage in 2015 compared to 2014 is filled with increased changeup and sinker usage. As I wrote back in January, Martinez's changeup had the potential to be the very best on staff, so seeing a nearly 100% increase in its usage (from 9.26% to 17.25%) is definitely a heartening adjustment. Going to the sinker more frequently was also viewed as an important addition because it would not only help with efficiency (in terms of inducing weak contact early in counts) but also his performance against left-handed hitters, with pitches diving down and away from their bats.
Results versus left-handed hitters
Much of 2015's improvement against left-handed hitters can be attributed to his sinker, which has helped lead to a near-league-leading ground ball rate (54.4%, sixth in MLB). That being said, do not dismiss the changeup's effect on Martinez's performance against left-handed hitters, either, as the pitch has held lefties to a .130 batting average and .110 isolated power over 100 at bats this season.
Dialing back on velocity (MPH)
Another consideration associated with durability was Martinez's velocity. It simply would not reasonable for him to throw 98+ MPH for six innings or more. Either his arm would fall off before the All-Star break, or he'd continually be removed from games in the third or fourth inning. As you can see, Martinez has dialed back the velocity on each of his four pitches, with the most notable being his high-powered fourseamer. With its average velocity still over 96 MPH, it's not like Martinez relinquished much of the pitch's potential, though, as only a handful of starting pitchers can boast about having that kind of velocity (i.e. Nathan Eovaldi, Garrett Richards, Matt Harvey, Gerrit Cole).
What is most impressive is that with his dialing back on fastball velocity, Martinez has dialed back on his changeup as well, which is necessary to keep the desired velocity gap between the two pitches. Of course, the arm speed of the two pitches should be the same, so it makes sense that his changeup has also been slower, but I wonder if his reported slight change in pitch grip plays a role here, too.
Leading to an increase in dragless horizontal movement (inches)
(Negative number: Movement to Martinez's arm side; Positive number: Movement to Martinez's glove side)
While it may not seem possible, Martinez's pitches have found a way to move even more than they did in previous seasons, and it is almost certainly due to his conscious dialing back in pitch velocity. Thus, while on the surface, a decline in velocity is typically viewed as a negative, Martinez has definitely turned his into a positive, a weapon to unleash as a consistently effective starting pitcher.
Regarding the huge difference in changeup movement, I once again believe this can be attributed to the new grip he is using with the pitch (shown here), plus the downtick in velocity. Martinez has definitely reaped the benefits of the increased movement as a changeup is at its best when it directly mimics the ball flight of a pitcher's sinker (if he has one, of course). As you may recall, it is nearly impossible to differentiate between El Gallo's sinker and changeup out of the hand.
Martinez has far exceeded expectations in his first full season as a member of the starting rotation. Don't get me wrong, it's not that I didn't think Martinez would be an effective starting pitcher. It's that I didn't realize he would be this effective, this quickly, with this many adjustments to his repertoire and approach. Honestly, if analysts don't realize that Martinez is wise far beyond his years after this season, then they never will because his evolution as a starting pitcher has truly been something to behold.
Credit to BrooksBaseball.net for data used in this post
P.S. Viva El Gallo.