Repertoires in review: Who has the best fourseam fastball on the St. Louis Cardinals?

I begin this week with what I intend on being a four part series in which I review (and subsequently rank) four different pitch types of St. Louis Cardinals pitchers. As the title of this post states, I will start with the pitch nearly every pitcher has—the fourseam fastball.

As you may be thinking right now, this exercise has basically already been completed by FanGraphs through their use of Pitch Values, but I think most of us can agree that assigning value to a given pitch is still very much an inexact science, particularly with the increased attention assigned to pitch sequencing, pitch tunneling, effective velocity, etc. Plus, we must remember that no one pitch holds value completely independent of one's other pitches, even Lance Lynn, who notoriously went an entire start throwing exclusively fastballs.

The basics (using 2015 PitchF/x data)

If a pitcher possesses a potential "staff best" pitch, he will likely throw it quite frequently. Thus, immediately, Rosenthal and Siegrist set themselves apart from the other pitchers included in this comparison, considering these two go with their respective fourseamers three out of every four pitches thrown. Rosenthal's staff-leading average velocity, combined with his frequent use of the pitch, gives the 25-year-old closer an early lead in the comparison.

In any discussion about fourseam fastballs, it would be a disservice to not include fastball-loving Lynn, and while he does throw the fourseamer more than any of his other pitches, he still utilizes his twoseamer/sinker more than you would probably think. I included Martinez because of his ability to hit triple digits (but as we will see below, it's not all that effective), Garcia because his fourseamer rates quite well by Pitch Value, and Walden because of his unique throwing motion and inherent ability to light up radar guns (despite providing us with a very small sample size last year).

2015 pertinent outcomes

When it comes to pitching, two things matter most: 1) inducing swings and misses, and 2) inducing weak (often on-the-ground) contact. Oftentimes, a pitcher is supremely good at one, but not so much the other (see: Garcia, Jaime). But if you look up and down both columns, it is pretty clear that Rosenthal has the healthiest mix of whiffs and on-the-ground contact with his fourseamer. While it looks like Walden is a close second, it is hard to take his 2015 numbers too seriously given that he threw only 10.1 innings before being lost for the season with an unspecified shoulder injury.

2015 results

While batting average against is definitely important to consider, I tend to put more stock in isolated power (ISO). The only batting average that stands out negatively is Martinez's, and as I stated earlier, the fourseamer just has not been an effective pitch for him yet. Comparatively, Rosenthal's batting average against is on the higher side, but his .091 ISO against shows that even though hitters may be reaching base, it's rarely more dangerous than a mere single. This, especially from the closer role, is particularly desirable.

Courtesy of The Pitcher List

I think I have made it pretty clear who I'd rank as having the number one fourseamer on staff. In all honesty, it was not much of a competition as other posts will lead to much more discussion. Either way, cast your vote below. If your favorite fourseamer was not included in the ballot, please discuss your choice in the comments section.