A Look At Mejia's First Start through Pitchf/x and What the Mets (and Mets Fans) Should Look For From Here On Out

AP photo of Jenrry Mejia from his start on Saturday against the Cubs. Image courtesy of SB Nation. 

Jenrry Mejia's first start in the major leagues this weekend did not look particularly impressive from a results standpoint: 

Five Innings Pitched, four earned runs, one unintentional walk, only two strikeouts (one resulting in the batter reaching anyhow on a wild pitch), and a not-particularly impressive 11/8 GB/FB ratio.

But what about the pitches themselves? Have they changed in the few months since we've last seen him? Did he use them differently? And does he show signs of what the Mets are working on with him? After the jump, we'll look at his pitches in his start against the Cubs, whether they've changed, and whether he's using them differently.

As a reliever, Mejia threw four pitches: a four-seam fastball, a two-seam fastball, a changeup, and a curveball. Below in Figure 1 is the graph showing the movement and speed of Mejia's pitches yesterday and Table 1 shows the average speed and movement on each pitch when Mejia was a reliever and as a starter on Saturday.

Figure 1: Graph of the movement and velocity of Mejia's pitches on Saturday. 

To Read:

Vertical movement: The amount of inches the ball drops/"rises" as compared to how we would expect gravity to make a pitch drop. So a fastball with Positive 10 Vertical Movement "RISES" 10 inches more than it should if gravity was the only force acting on it and a curveball with -10 Vertical Movement drops 10 inches more than a pitch thrown that is just acted on by gravity.

Horizontal movement: The graph is from the view of a catcher or umpire behind home plate. So a pitch that's on the left side of the graph (and has "negative horizontal movement") moves in on righties and away from lefties. A pitch that's on the right side of the graph moves in on lefites and away from righties. 

Legend for this Graph and All Subsequent Graphs:
Four-Seam Fastballs = Red Dots
Two-Seam Fastballs = Yellow Dots
Changeups = Green Dots
Curveballs = Blue Dots

Table 1:  A table showing the average movement and pitch speed of each of Mejia's pitches as a starter and as a reliever. 

The first thing you should notice is that Mejia's velocity was down significantly on his fastballs in his start on Saturday. The Mets have tried to spin this as the result of Mejia changing speeds, but that's not really the case; in reality, he just simply could not get the velocity on his pitches that he had before as a reliever, never even hitting 95 on the gun even once. This is of some concern. Mejia's fastball was remarkable for two reasons: its cutting movement and its velocity. The combination of the two that he showed before was essentially unique. Among all pitchers in the major leagues this year, only Evan Meek of the Pirates managed to have a pitch that was similar in speed and movement to Mejia's. 

It would be disappointing if Mejia was to have such a lower velocity as a starter, but at least the MOVEMENT on Mejia's four-seam fastball remains the same as a starter (roughly). The pitch cuts, so that the pitch is essentially moving away from right-hand batters like a slider instead of toward those right-handed batters like a normal fastball. Mejia's two-seam fastball and changeup move a little more like a traditional fastball, but still don't move very far in on right hand batters. 

Finally, you should note that Mejia was more willing to use his secondary stuff in his lone start than he did as a reliever. His curveball use increased a good bit in his start and he used the pitch equally against right and left-handed batters. Moreover, he showed some more accuracy with the pitch on Saturday (in fact, he showed almost too much accuracy, hitting the strike zone 75% of the time with the pitch). The movement on these pitches appears essentially the same as it was when he was using them sparingly as a reliever.

What we and the Mets should be looking for in Mejia:

Here are two quotes from Adam Rubin's recap of Mejia's first start:

"The Mets had dispatched Mejia to the minors to polish his curveball. They also wanted him to hone his changeup and a four-seam fastball so that it would break in on right-handed batters and offset the cutting action away from them on most of his pitches. Although Mejia drew positive reviews in the minors, Manuel and pitching coach Dan Warthen indicated the secondary pitches remain works in progress."

"Said Warthen: 'Most all of his balls cut. We want that two-seamer to move the other way.'"

The second "quote" is direct from Dan Warthen. And the second quote is not a bad one: it maintains the idea that Mejia should have a two-seam fastball that more clearly breaks in on right-handed batters to contrast with his cutting four-seam fastball. Right now, the two-seam fastball does break more in on RHBs than the four-seam pitch, but not by that much. If he could clearly separate the two pitches, he might be able to have greater success. For reference, one pitcher in the majors who uses a two-seam fastball and a cutting fastball that go in very-opposite directions is some guy named Roy Halladay (Jon Niese also might fit this profile, but he has a four-seam fastball that is in the middle of his two opposite-moving pitches). Asking for Mejia to be Halladay might be a little bit much, but we should look in his next few starts whether he's able to make the two-seam fastball move more in on right-handed batters so that it is more clearly a separate pitch. 

The first quote, if correctly transcribed, would be a little worrisome. Mejia's great potential lies in the fact that his fastball cuts and sinks. If they were to try and make his four-seam fastball move more in on right-hand batters, it would take away that great cutting action that gives him his high potential. I hope that this quote was simply Adam Rubin mistaking Warthen's talk about the two-seamer for the four-seamer. 

Conclusion:

The Mets and their fans have a lot to be interested in in Mejia.  During this last month of the season we ought to look at four things: 

1)  Can he get his velocity back up on his fastball?
2)  Can he separate his two-seamer's movement from his four-seam fastball's cutting movement? 
    2a)  Can he do so without losing his great cut on the four-seam fastball?
3) Can he learn to use the curveball and changeup more effectively so that he has a larger arsenal?

He will probably make about four more starts -- this is pretty exciting. Let's just hope the Mets don't screw him up.