Deep Dive: What's going on with Brayan Bello?
Brayan Bello is in the midst of one of the worst months of his young career, with the exclamation point coming on Tuesday night vs Toronto. It was the second-worst outing of his career, with 7 earned runs in just 2.1 innings pitched. The outing prompted many to start questioning what is going on with Bello this season. Let’s look under the hood and see what clues we can find out about Bello’s tough year.
For starters, let’s deconstruct Bello’s 2023. In his first full MLB season, Bello finished the year with a 4.24 ERA and 4.54 FIP in 157 IP (28 starts). For those who like expected stats, his xERA was 4.16 and xFIP was 4.02. His K% was 19.8% (26th percentile) and his BB% was 6.7% (76th percentile). His GB% was 92nd percentile at 56.3%.
Basically, what you got out of Bello on the whole was a ground ball pitcher who kept the ball in the zone but didn’t get a ton of strikeouts. On a team with as poor infield defense as the 2023 Red Sox, it was easy to see why his expected stats were lower than his traditional ones. This was a season you could build on, and as a 24-year-old there was plenty of room to grow. Drilling down one level further brings us to our biggest growth area for Bello, his performance vs. left-handed hitting:
You can see by the numbers; Bello was much better vs right-handed hitters than he was vs left. This is where we can start to talk about Bello’s pitch mix. Bello’s three main pitches are his Sinker, Slider, and Changeup. In ’23, he was also mixing in a Four-Seam Fastball and briefly experimented unsuccessfully with a Cutter. Below is how he attacked vs right and left on the whole during the ’23 season:
The main takeaway here is that Bello really didn’t have much else besides the changeup that worked against left-handed hitters in 2023. Against righties, he could lead with the sinker at 95 mph and then drop down to either the Slider or Change at a lower velocity band. The slider would move to his glove side and the change would move to his arm side, creating a guessing game that made it difficult for righties to square up. Against lefties, however, Bello spent the season trying to determine which of the sinker or four-seamer would best compliment his change, not really finding consistent success with either:
Now let’s look at how things are differing for Bello in 2024, where he is currently sitting with an inflated 5.55 ERA and 4.83 FIP through 14 starts. His K% is about the same as 2023, at 20.1%, but his BB% has ballooned to 9.1%. His GB% has remained stable, coming in at 54.3% and maintaining its 92nd percentile status. For those who like expected stats, his xERA is 4.37 and his xFIP is 3.96. Wait… what? His xERA isn’t that much worse than it was in 2024 and his xFIP is actually better? What’s going on here? I may have found at least somewhat of an explanation.
First, here is Bello’s performance vs righties and lefties in 2023 vs 2024:
What sticks out to you here? To me at least, the thing that sticks out the most is how remarkably similar some of the figures are. You’ll see that righties appear to be faring a bit better vs Bello this year, but that the FIP and xFIP numbers vs RHH are within .01 points of each other in 2023 and 2024. This can be partially explained by the additional stat that I brought in here, BABIP, which is often used as a proxy for luck.
This suggests Bello’s results were perhaps a bit on the lucky side vs RHH in 2023 and is a little closer to the unlucky side vs RHH in 2024. Against LHH, batters have nearly the same OPS and wOBA vs Bello this year, but the BABIP, FIP, and xFIP numbers suggest Bello was on the unlucky side vs lefties last year and that he may have regressed a bit this year. Still, outside of the walks and a shift in strikeout distribution this looks a lot like the pitcher we saw last year. Let’s next look at how the repertoire has changed under Andrew Bailey:
Two things stick out, besides the fact he’s scrapped the four-seam fastball and the cutter, which most Red Sox fans were already aware of. One, Bello’s sinker and changeup have very similar movement profiles, and they are less than 10 mph apart on average. The changeup is being thrown about the same amount to righties, but is less effective this year.
This could be a side effect of dropping the four seamer, because hitters know that if they can pick up the slider, any other offering will move to Bello’s arm side. All they need to do from there is adjust to the speed. It’s worth noting that Bello started off the season throwing the change up 26.8% of the time to righties, and that number has come down significantly to 12.7% in June, so more recently he has been throwing mostly just two pitches to RHH.
The other thing that sticks out is that the movement profile on the slider has changed. Last season the slider had a 42.3-inch vertical drop and 3.7-inch horizontal break. This year it’s dropping less vertically and breaking more horizontally, moving closer to a sweeper-like profile. Though this iteration of the slider has produced more whiffs (34.5% this year vs 29.5% last year), it has also produced more walks (8.9% vs 5.1%) and line drives (34.1% vs 16.7%), and fewer ground balls (38.6% vs 61.1%). All of this could be telling us that Bello is having a hard time commanding his new breaking ball.
So, we’ve examined the changes in Bello’s arsenal, and we’ve determined that his overall numbers vs both righties and lefties are generally in the same ballpark as last year, save for some additional walks to batters on both sides. The walks are obviously not desirable, but they shouldn’t account for over a full run’s worth of ERA year over year. Rather, the real story is what’s happening when runner’s get on base:
You can see in the chart above that when the bases are empty, Bello is actually outperforming his 2023 numbers, even with the extra walks and a higher BABIP in those situations in 2024. Where things begin to unravel is when runners are on base, and worse, when runners are in scoring position. These situations famously produce more runs, and they’re having an outsized impact on Bello’s ERA as a result.
The numbers in these situations are inflated year over year against batters from both sides of the plate, but they are particularly inflated vs left-handed hitters, as has been a theme throughout this article. This is the part where I finally let Bello off the hook – at least a little bit -- however. Last year in situations with Runners in Scoring position, Bello faced a left-handed hitter just 42.5% of the time. This season, he’s faced a LHH 47.8% of the time in his RISP situation. Now, Bello is still getting into RISP situations more frequently, and that’s on him. However, it greatly exasperates the problem when he sees more lefties in more dangerous situations, since LHH are his biggest issue.
The thing I found most interesting is that Bello improved against both righties and lefties with the bases empty. It’s possible that there’s a mechanical adjustment Bello needs to make in the stretch position. MacKenzie Gore of the Washington Nationals is an example of a pitcher who made mechanical adjustments from the stretch this year and is seeing much better results with runners on base. Perhaps Bello’s timing in his delivery is off in the stretch, much like Gore’s was, and it’s causing Bello to miss spots more often in those situations. That’s just speculation on my part, but it would be an interesting area to dig for more.
If there’s one thing I hope you take away from this article, though, it’s that Bello’s most glaring issue is not a new development. This isn’t so much a case of a guy who has a new and unforeseen issue post contract extension, but rather a case of a player who’s pre-existing deficiency is being exposed in more damaging situations. The biggest thing keeping Bello from his best self is the same as it was last year, he needs a new offering to left-handed hitters. Bailey took his first crack at fixing the issue this year, and so far it hasn’t worked. That on its face is not something to be overly discouraged about, but they will have to get back to the drawing board and try something new moving forward.
