Jacob deGrom threw ten pitches off the mound in Atlanta on Saturday after playing catch on Friday. However, there is still no official target date for his return to the rotation.
“We’re just going to take it day-by-day,” deGrom said. “I felt good today, so I just wanted to throw light off the mound and just see how it reacts Sunday.”
Confession time – despite my mother’s strongest urgings, I am not a doctor. I also have never spoken with Jacob deGrom, seen his medical records, nor spoken with team doctors. However, by looking at publicly available pitching statistics from FanGraphs, I can reasonably conclude that Jacob deGrom was likely pitching with an injured arm prior to his most recent start on September 1st.
Basis of Analysis:
On August 7, deGrom pitched 6 2/3 innings against Detroit in Detroit, allowing only 1 earned run and walking three. On August 13, against the Padres, DeGrom pitched seven innings against the Padres, allowing only three hits, one earned run and striking out nine. These two recent starts will serve as the “healthy” baseline.
On August 18th, DeGrom allowed eight earned runs and 13 hits in five innings against the Giants on the road and on August 24th, in 4 2/3 innings allowed 12 hits and five earned runs against the Cardinals. These two starts will be our “Possible Injured Condition.”
On Sept 1, against the Marlins at Citi Field, deGrom allowed three earned runs in five innings against the Marlins. After leaving the gamed deGrom was seen motioning to the team’s trainer and for our analysis will serve as the “Injured Condition.”
A deteriorating arm will have, in order, an impact on release point, movement of pitches, and finally velocity. This article will investigate all three to indicate whether Jacob deGrom may have been pitching with a hurt arm before he and the Mets publicly admitted it.
Release Point:
The chart below reflects Jacob deGrom’s release point by pitch type during his healthy August 7 start against the Tigers:
CHART A
Note that the cutter (CU) has the highest vertical release point and that for all of his pitches cluster between 5.5 and 6 inches with none all that close to 5 inches.
In Chart B below from deGrom’s August 24th start against the Cardinals, note that the fastball (FA) now has the highest vertical release point and the cutter is not as high. Actually, the vertical release point is not as high as it was on August 7th for any of the pitch types, most release points were much closer to 5 inches.
CHART B
The chart below is from the Sept 1 start, after which it was reported that deGrom would need to miss a start and was suffering from elbow inflammation:
CHART C
Again, the release point is lower than it was in the healthy baseline of the first chart and in that start his horizontal release point was much closer to zero than it was in either of the previous charts. T the changes in both vertical and horizontal release points indicate that it is possible deGrom was experiencing pain in his arm prior to the September 1 game against the Marlins.
Movement:
Horizontal Movement: In the following chart, negative numbers reflect arm side movement (fade) and positive numbers are moving, from the pitcher’s perspective, from right to left:
Note that the horizontal movement of the slider and cutter declined in the two “Possible Injured” starts (likely why they were poor starts) and the fade increased on the fastball and changeup, likely too much movement out of the strike zone and was why the hitters were constantly in hitting counts.
Vertical Movement: The following chart reflects the vertical movement on DeGrom’s pitches:
In the two Possible Injured starts, there was less movement on the fastball, slider and cutter, indicating that deGrom was either pitching with a sore arm and not admitting it, or his or his arm was not hurt but the changes in release point was impacting the movement on the pitches.
Velocity:
The following chart reflects deGrom’s velocity in each of our three breakdown categories over his last five starts:
Note that his velocity actually increased in the two bad starts against the Giants and Cardinals, but the velocity of all four pitch types declined somewhat dramatically in the September 1st start which is indicative that deGrom was pitching with a sore arm. Taken together with the changes in arm slot in changing movement on all pitch types, the health of deGrom’s arm had likely been deteriorating prior to September 1.
