Cody Bellinger won an MVP as a 23 year old in 2019. He was inarguably one of the ten best players in the game, and he seemed like a surefire hall of famer with a real chance to break some records. Flash forwards three years and Cody Bellinger is a below-average hitter who was just benched in an elimination game because the Dodgers had so little confidence in his bat. And rightfully so, as Bellinger has a 64 OPS+ over his last 239 games.
So what happened to make Bellinger fall apart so suddenly? To identify that we first have to identify exactly when he regressed. The first instinct might be to point towards 2020 when he hit just .239/.333/.455 the year after winning MVP as the beginning of the end. However, Cody Bellinger still had a .374 xwOBA that was in the 85th percentile and the second-best year of his career. His top-end EVs were just as high in 2020 compared to 2019 and his contact rate was actually higher. The only thing that regressed was his line drive rate and his plate discipline. Both of which fell in the standard range of ebbs and flows over a 60-game stretch.
Celebrating is Dangerous
The most commonly identified culprit for Bellinger’s spontaneous regression is his dislocated right shoulder. He suffered it in game seven of the NLCS in 2020 doing a shoulder bump with Enrique Hernández after hitting a home run. This is something both Dave Roberts and Brant Brown have blamed for his struggles. This is the theory that I myself believed for a long time, the timing lines up almost perfectly and we’ve seen the career-altering effects of shoulder injuries many times in the past. Blaming it on the shoulder makes it hard to see a road to improvement, and provides an easy explanation for his spontaneous drop off.
However, there are a few problems with this explanation. The first and most prominent is that after dislocating his shoulder in 2020, Cody Bellinger had a batted ball with a 111.2 MPH exit velocity in the World Series. He also hit 107.8 MPH and 107.7 MPH in that same three-game set. All of those batted balls have a launch angle above 0° so it’s unlikely that they are misreads. Yet, playing with a dislocated shoulder, he had three batted balls harder than a single one he hit in either 2021 or 2022. If the shoulder is to blame then would surgery make it worse? It might cause it to heal wrong but it wouldn’t be worse off then with a tear. The other sign is in his bat path.
When Eugenio Suárez and Matt Chapman were dealing with shoulder injuries, their VBA (Vertical bat angle) got about 3° flatter. Bellinger has almost the same exact VBA this year as he did in 2020 before the shoulder was busted. The shoulder injury might be a contributing factor but it can’t be the sole cause of his offensive regression.
The Actual Culprit?
So when did the regression actually happen? Cody Bellinger still had more power in the spring of 2021 than he showed in all of the regular season (or postseason) that year, or the year after. He only had 9 batted balls with Statcast during the spring of 2021, but in those nine batted ball events he topped out at 107.5 MPH on a home run. He hit another home run at 106.2 MPH this spring. Those aren’t eye popping numbers but given the context, they are. Cody Bellinger has topped out at 107.4 MPH since the start of the 2021 regular season. He has hit a ball at least 106.2 MPH just nine times. This is a 608 BBE sample. The difference in power output is absolutely massive in such a short period of time.
So why did his power fall off so dramatically in under a month? We were correct to blame injury, but we assigned blame to the wrong one. Reymin Guduan spiked Cody Bellinger during a close play at first base on April 5th. Bellinger fractured his left fibula.
That was when everything fell apart for Bellinger, as that one injury that sidelined him for nearly two months also ruined his mechanics.
Healthy Enough to Play Doesn’t Mean Playing is Risk-Free
The same day that it was revealed that Cody Bellinger had a hairline fracture in his left leg, it was revealed by Dave Roberts that Bellinger was still taking swings and working out even after finding out his leg was broken. He said the rehab drill would remain the same as they had been before they got the diagnosis.
The Dodgers likely had a team of specialists who analyzed Cody Bellinger’s leg and determined that it wasn’t going to get any worse if he took swings while it healed. I’m not going to say they were at all wrong, but actions often have unforeseen consequences. The risk of Cody Bellinger swinging with the broken leg wasn’t that his leg gets more broken, it was that pain teaches him bad habits.
Nine months ago I got posterior tibial tendonitis. The injury left me unable to walk for a few days, but once I could move, even in pain I did so. I didn’t exercise, but I also didn’t use crutches or keep weight off my left foot. The injury healed just fine within the promised six-week timeframe, even if I was more active than I maybe should have been.
However, because I was trying to be active with a hurt foot, I subconsciously altered the rotation of my right foot when I was walking or even just standing, so it was pointed outwards slightly. This put more of my weight on the right side than the hurt left one, and made my life slightly easier. It isn’t something I did intentionally, it just kind of happened without my noticing until I noticed it when someone took a picture of me months later.
Flash forward nine months without any pain in my foot whatsoever, and I still stand with my right foot rotated outwards and most of my weight pooled on that leg. I have to consciously try to keep my feet straight or I default to that position. The injury is long gone, but the muscle memory of avoiding pain has lingered for months after the fact. Had I chosen to use crutches until the pain was more manageable, I likely wouldn’t have any weird posture. Instead, the moment I was able, I walked as close to normally as possible and that messed up my muscle memory. I believe this is what also happened to Cody Bellinger, but in a much more impactful way then just standing funny.
Similar but Different Mechanics
At first glance it probably doesn’t appear like Cody Bellinger’s batting stance has changed a ton since his MVP season in 2019. That is probably because it hasn’t. Almost everything in his initial stance is the exact same. So is almost everything in his swing. His VBA is 0.1° higher than it was in 2020, hardly a significant deviation. Let’s do an experiment. Here are two Cody Bellinger videos, one is from 2019 and the other is from 2022. Can you guess which one is which?
The first video was 2022 and the second was 2019. The two swings are nearly identical cosmetically when looking at full speed and normal TV camera angles. The two swings are not the same, but it’s understandable why the assumption is just shoulder injury, the swings are too similar for there to be a major mechanical change right?
Wrong. The reason why the swings look so similar at a surface glance is that the upper body is the same, and the leg kick is the same. Those are the two things that your eyes naturally gravitate towards when watching a swing- for obvious reasons. They’re flashy and where the most movement occurs. However, the upper body is only half of a swing and the same-sized leg kick doesn’t mean it’s just as effective. Baseball is a game of inches, and Bellinger’s adjustments to protect his once-injured leg can only be seen if you look at his swing one frame at a time.
The Initial Position
When comparing Cody Bellinger now and in 2019 from the side view, unless specified otherwise it will be with these videos from PastimeAthletics on YouTube. This wouldn’t have been possible without them uploading so many side-views of hitters mechanics. Pro Tip: You can go one frame at a time by pausing the video and using . or , to navigate forwards and back a single frame.
The left image is 2019 and the right is 2022. You can clearly see that on the right, Bellinger’s stance is slightly wider. The benefit of a wide stance is better timing and bat control (in theory) the benefit of a more narrow stance is typically more power as they are striding further and starting with their weight more on the back leg. When Bellinger hurt his left leg he came back with a slightly wide stance. Why? To avoid putting too much weight on his back leg when he strides and causing himself pain. That was hardly the most impactful chance to his starting position though.
Take a look at Bellinger’s drive foot. Notice something different? Let’s try zooming in a bit more, in case it wasn’t obvious.
Cody Bellinger is seemingly now rotating his drive leg slightly more towards the pitcher. What does that internal rotation do? Rather than explain it to you, I’ll have you discover it for yourself. Stand up with your feet shoulder width apart and parallel to each other with your feet pointed straight forwards. Now rotate your left leg inwards slightly. Do you feel the weight shift to your right leg? If you can’t feel it then try raising on your tiptoes one leg at a time. Notice how it’s a lot easier to lift the left leg to tiptoes compared to the right. This is because with the foot rotated like that, your weight naturally pools slightly more on the right side of your body. You can still shift your weight to the back leg by flexing the knee, but in an upright stance, the weight starts on the right side.
Foot Strike
I think it’s easy to assume that the top half is moving slower now because his swing is further along at foot strike now. I think that assumption is false. The difference in swing progression at foot strike has less to do with delayed upper body rotation, and more to do with him needing to stride a shorter distance from a wider base. If we measure his old swing by when his feet were as far apart (Mid-stride) as they are to start now, we find that the difference in time to foot strike is just 8 frames longer now (30 FPS but video is initially uploaded at ~10% speed so it’s actually closer to 300 FPS for these purposes- the difference is nonexistent). He hasn’t slowed down the top half, he’s just shortened the movement of his lower half.
This creates a disconnect in Bellinger’s swing. There is a brief window after his heel strikes where Bellinger is neither moving his top half or lower half. It’s incredibly brief, but it can cause some of the power built by his stride to leak out uselessly. The old Bellinger started to move the top half the moment his toe hit the ground and his heel hit as the shoulder was dropping this down. This made it totally natural for Bellinger to swivel on the back foot as the hips fire and the shoulder drops into place.
Heel Lift
Here is the picture of where Bellinger is at now when his top half catches up to 2019 Bellinger. Pay attention to his left leg. He’s much less tense now with some of his weight being redistributed to the front half. Now let’s zoom in for a second.
Notice how his drive leg comes off the ground so early in the swing. Almost all hitters lift the drive leg at some point but it’s usually later in the hip rotation, and right before the bat enters the zone. Bellinger lifting prematurely is shifting his weight to the front side early and hurting his ability to accelerate the bat. This is why he has struggled so much with velocity in the last two years. He’s struggling to get good acceleration due to an ineffective weight transfer, and as such has a really hard time hitting velocity. For comparison, let’s look at 2019 Bellinger and when his drive foot leaves the ground.
Notice how much further along Bellinger’s hip rotation is in the second image and how his bat is about to enter the hitting zone. Bellinger pushing off later let him use it to propel the bat at the most crucial point, and to complete the hip rotation. The earlier push off slows the hips instead, and wastes his once incredibly powerful backside.
Point of Contact
Here is Cody Bellinger at the point of contact on two fastballs in the same location that were driven over the right field wall for a home run. The left image is 2019, and the right image is 2022. Take a look at Bellinger’s left leg and the difference in posture there. He has a lot more flexion in the knee now (Pitch location isn’t the same so it only kind of works, but he has ~11° less bend in 2019 on a slightly higher pitch from a side view) because the foot is rotated inwards more, and it puts more of the onus of the swing on his front side.
The early weight on the lead leg causes him to rotate with it rather than around it. Take a look at the positioning of his front foot during the follow through of both swings, notice how in one he stays planted but in 2022, he spins on the heel after making contact. This sacrifices the stability of his base, and likely hurts his ability to finish as well.
The Impact of Damaged Mechanics
The most problematic element of Bellinger’s swing now is a weight transfer that used to be amongst his biggest strengths. An inefficient weight transfer can lead to instability in the bat path. This is why Bellinger is hitting so many more mishits despite contact rates in line with his career norms, and his bat angle not changing at all. The inconsistent attack angles because his weight transfer isn't consistent have led to him frequently swinging underneath pitches in recent years. This is why the wOBAcons are down so much, more than anything else that might have changed.
Cody Bellinger’s top-end power has also regressed significantly. He has gone from a 90th percentile exit velocity of 105.1 MPH in 2019 to 102.2 MPH in 2022. This is likely because his top half is now disconnected from the lower half. His wider stance has left his hand running late after the stride, and as such he’s not generating any effective power with his stride anymore. This is likely why his top-end bat speed, and as a result, his exit velocities are down so much.
The root of Bellinger’s regression in strikeout rate is twofold. First off, he has forgotten how to hit fastballs. His in-zone whiff rate is up 5,5% this year compared to his MVP season. This is the only pitch he has significantly more in-zone whiffs against now. His breaking ball whiff rate has climbed by just 1.6%. His offspeed whiff rate has actually improved by 12.7% in the strike zone since 2019. It’s easy to blame the uptick in whiffs against fastballs on the disrupted timing caused by the shorter stride, and his lack of acceleration of the bat because of the premature weight transfer.
We can also prove that his mechanical regression took place after the leg injury. Take a look at this video from the first game of 2021. Look at his feet positioning. Look at when the back foot leaves the ground. It’s not quite a perfect mirror of 2019 but it’s a lot closer to MVP Bellinger than the modern Bellinger.
So What’s Next?
Cody Bellinger is broken, there is no disputing that. He messed up his leg through no fault of his own, and the Dodgers handled his rehab logically- with the Giants in the process of overtaking them. The doctors didn’t mess up in clearing Bellinger to swing, they just didn’t account for the possible side effects of clearing him to play. Usually, these side effects don’t manifest. Bryce Harper is playing with a torn UCL right now and has been one of the best hitters in baseball. Pain doesn’t always cause things to break. Bellinger was broken and there’s no one to blame for it, it just happened.
His broken state doesn’t have to be permanent, however. The upside that saw Cody Bellinger win an MVP still exists within him, he just has to get back to who he used to be. So how likely is that? That is not a question I can answer. If we assume Bellinger is perfectly healthy now, it still doesn’t resolve his problems. Muscle memory is a hard thing to change, and Bellinger has been like this for two years now. Is it too late? It’s a real possibility.
I would expend every resource available to get his mechanics back to where they were and make small adjustments, but success is far from a guarantee. The hope is that you can at least find a middle ground, and get him somewhere between the awful hitter he’s been the last few years, and the MVP he once was, with an eye on eventually returning him to peak form.
The Dodgers have a tough decision ahead of them this offseason. Do they give Bellinger twenty million in hopes of him finally bouncing back? Or do they let someone with MVP upside walk, given that the likely outcome is a below-average regular? How much does a different team offer him in pursuit of an MVP player if they choose the latter path?
My preferred course would be to try to bring Bellinger back at a base pay below the arbitration estimate, but with incentives to push him over if he performs. The upside is too high to just cut bait entirely. Even if he’s only a slightly above-average hitter, he’s an all-star with his elite defense in centerfield. There are still unanswered questions for Bellinger, but even if this is the end of his time with the Dodgers, this is not the end of his story. Cody Bellinger has fallen, but that doesn’t mean he can’t rise again from the ashes.
All observations here are my own, and not at all sourced from anyone else in baseball. I am making educated guesses based on the information I have available to try to solve the mystery of what happened to Cody Bellinger. I believe my theories, but I fully acknowledge the possibility that I am wrong about what happened or how to fix it.