Previously, I've noticed that some right-handed pitchers can't seem to get lefties out. While their overall stats seem reasonable, lefties light them up. I did a small study to see if I'm imagining the phenomenon or if there is anything there. Also, I examined some of the pitchers who struggle to get lefties out.
For the sample size, I looked at right-handed starters with at least 20 innings pitched this season. Then I found the difference in their K%-BB% when facing lefties and righties. I grouped these differences by magnitude and compared their ERA-xFIP.
There wasn't any measurable difference in ERA-xFIP until I got to the pitchers whose K-BB% versus lefties is more than 10 points worse than their K-BB% against righties. On average, these starters posted an ERA 0.41 points higher than their xFIP. Below this threshold, there was no noticeable difference.
While I had the data, I examined the percentage of lefties and righties these pitchers faced, and the amount of plate appearances against lefties hovered just under 60 percent. By grouping these amounts, the ERA-xFIP values didn't differ.
Here on the right-handed starters who are struggling against lefties and my thoughts on some of them.
| Name | IP | ERA | xFIP | ERA - xFIP | K-BB% | LH% | K%-BB% (vs LHH) | K%-BB% (vs RHH) | Difference |
|---|---|---|---|---|---|---|---|---|---|
| Max Scherzer | 22 | 10.23 | 6.26 | 3.96 | 2.9% | 68% | -2.9% | 15% | -18.1% |
| Tyler Glasnow | 39 | 2.72 | 2.90 | -0.18 | 24.3% | 64% | 17.9% | 36% | -18.0% |
| Grayson Rodriguez | 25 | 8.06 | 4.86 | 3.21 | 7.3% | 54% | 0.0% | 16% | -16.1% |
| Lucas Giolito | 20 |
Previously, I've noticed that some right-handed pitchers can't seem to get lefties out. While their overall stats seem reasonable, lefties light them up. I did a small study to see if I'm imagining the phenomenon or if there is anything there. Also, I examined some of the pitchers who struggle to get lefties out.
For the sample size, I looked at right-handed starters with at least 20 innings pitched this season. Then I found the difference in their K%-BB% when facing lefties and righties. I grouped these differences by magnitude and compared their ERA-xFIP.
There wasn't any measurable difference in ERA-xFIP until I got to the pitchers whose K-BB% versus lefties is more than 10 points worse than their K-BB% against righties. On average, these starters posted an ERA 0.41 points higher than their xFIP. Below this threshold, there was no noticeable difference.
While I had the data, I examined the percentage of lefties and righties these pitchers faced, and the amount of plate appearances against lefties hovered just under 60 percent. By grouping these amounts, the ERA-xFIP values didn't differ.
Here on the right-handed starters who are struggling against lefties and my thoughts on some of them.
| Name | IP | ERA | xFIP | ERA - xFIP | K-BB% | LH% | K%-BB% (vs LHH) | K%-BB% (vs RHH) | Difference |
|---|---|---|---|---|---|---|---|---|---|
| Max Scherzer | 22 | 10.23 | 6.26 | 3.96 | 2.9% | 68% | -2.9% | 15% | -18.1% |
| Tyler Glasnow | 39 | 2.72 | 2.90 | -0.18 | 24.3% | 64% | 17.9% | 36% | -18.0% |
| Grayson Rodriguez | 25 | 8.06 | 4.86 | 3.21 | 7.3% | 54% | 0.0% | 16% | -16.1% |
| Lucas Giolito | 20 | 4.35 | 6.61 | -2.26 | -4.2% | 51% | -11.3% | 4% | -15.7% |
| Brandon Young | 72 | 3.11 | 4.62 | -1.51 | 9.6% | 61% | 3.7% | 19% | -15.5% |
| Reynaldo Lopez | 24 | 3.65 | 4.93 | -1.28 | 9.3% | 55% | 2.7% | 18% | -15.1% |
| Jack Flaherty | 70 | 4.97 | 4.46 | 0.50 | 15.3% | 54% | 8.5% | 23% | -14.8% |
| Edward Cabrera | 72 | 5.10 | 4.07 | 1.04 | 11.7% | 61% | 6.3% | 20% | -13.7% |
| Aaron Nola | 85 | 6.04 | 3.99 | 2.05 | 15.4% | 58% | 9.6% | 23% | -13.6% |
| Aaron Civale | 67 | 5.05 | 5.17 | -0.11 | 9.2% | 58% | 3.4% | 17% | -13.5% |
| J.T. Ginn | 81 | 2.98 | 4.12 | -1.15 | 11.8% | 59% | 6.0% | 19% | -13.4% |
| Mike Burrows | 89 | 5.64 | 4.79 | 0.85 | 9.6% | 57% | 4.4% | 17% | -12.6% |
| German Marquez | 29 | 5.76 | 5.46 | 0.30 | 5.5% | 56% | 0.0% | 13% | -12.5% |
| Luis Castillo | 65 | 4.82 | 4.37 | 0.45 | 13.8% | 58% | 8.7% | 21% | -12.3% |
| Tatsuya Imai | 47 | 5.36 | 3.70 | 1.66 | 16.3% | 60% | 11.5% | 24% | -12.3% |
| Troy Melton | 37 | 2.39 | 4.64 | -2.25 | 11.0% | 63% | 6.6% | 19% | -11.9% |
| Merrill Kelly | 81 | 5.84 | 5.35 | 0.49 | 3.9% | 58% | -1.0% | 11% | -11.5% |
| Jameson Taillon | 67 | 5.19 | 4.71 | 0.48 | 12.5% | 50% | 6.9% | 18% | -11.2% |
| Brayan Bello | 35 | 10.35 | 5.53 | 4.82 | 0.5% | 58% | 2.4% | 14% | -11.1% |
| Zack Littell | 56 | 6.07 | 5.59 | 0.48 | 6.4% | 55% | 2.1% | 13% | -10.8% |
| Walbert Urena | 70 | 3.21 | 4.17 | -0.95 | 11.1% | 51% | 5.0% | 16% | -10.8% |
| Zack Wheeler | 75 | 2.03 | 3.31 | -1.28 | 19.4% | 62% | 15.4% | 26% | -10.3% |
| George Kirby | 104 | 3.81 | 3.62 | 0.19 | 15.5% | 52% | 10.6% | 21% | -10.3% |
Grayson Rodriguez: Before he returned to the injured list, lefties had a 1.088 OPS against Rodriguez compared to a .733 OPS from righties. A zero percent K-BB% against lefties is never going to cut it. He's never had issues against lefties in the past, so I tried to figure out what had changed.
Compared to previous seasons, he is throwing his four-seamer seven percentage points more. Also, his groundball rate is down from 41 percent to 33 percent. There are changes, but they don't explain the extreme difference.
The symptoms are obvious, but I can't find a cause that, if fixed, would solve the problem. I know some fantasy managers are waiting on his return, but I'm going to monitor from afar.
Lucas Giolito: Against lefties so far, he has just a 3.1 K/9, and his fastball velocity is down 2.4 mph from last season. Besides the lack of strikeouts against lefties, he is walking everyone, with an 8.0 BB/9 against lefties and a 6.0 BB/9 against righties.
There is so much going wrong here. Ignore him.
Brandon Young: Young might be one of the most overperforming pitchers this season, with a 3.11 ERA and 4.66 xFIP. Additionally, his 1.30 WHIP is doing as much ratio damage as a 4.34 ERA would do.
While Young only as a four percent K%-BB% against lefties, he has been able to limit damage thanks to a .228 BABIP.
While the differences are notable, he has made some recent changes to his splitter. Since the change, he has a 2.35 ERA and 4.10 xFIP. Hold for now as he transitions to a new power level.
J.T. Ginn: While Ginn has been dealing with a major split this season (3.55 xFIP vs. righties, 4.70 xFIP vs. lefties), he also lost his ability to throw strikes over the last seven games, with a 4.6 BB/9 over that stretch. The walks, along with additional hits from a 46 percent groundball rate, put him at 1.42 WHIP, which does as much damage to your roster as an ERA over 5.00. During the offseason, I examined these high-walk, high-groundball types and how they can hurt a fantasy team.
Over his career so far, he has not been able to get lefties out, with 4.65 xFIP against them compared to a 3.10 xFIP against righties. Previously, teams didn't push all in on the lefties against him, but they do now. In 2024, he faced 53 percent lefties, and it dropped to 47 percent lefties last year. This year, 59 percent of the batters he's faced have hit left-handed.
We'll see if he can keep the results going. A hold if WHIP isn't an issue, but a possible drop if a manager needs to improve their WHIP.
Aaron Nola: Nola just can't help himself from walking lefties with a 5.0 BB/9. While he's shown a split over his career (3.0 BB/9 against lefties vs. 1.8 BB/9 against righties), this year it's gone to a new level.
Since his combined fastball velocity has dropped below 92 mph the past two seasons, he's getting destroyed by hitters from both sides of the plate for a combined 6.02 ERA, .321 BABIP, and 1.9 HR/9.
He's trying to make changes. Over the last four games, he dropped his cutter and added a slider, but the results didn't change (6.63 ERA, 4.75 xFIP, 1.63 WHIP). If Nola is still on a roster, he's an immediate drop.
George Kirby: Kirby is fine against lefties, but his "struggles" against them are keeping him from being one of the league's best pitchers. Here are his monthly pitch type usages against left-handed hitters over the years:
The two big changes this season are the continued decline in four-seam usage and dropping his splitter for a changeup.
One other factor to account for is that he is generating more groundballs, with his groundball rate up from 44 to 49 percent, but many are going for hits because the Mariners have the league's worst defense this year (-26 OOA).
Kirby keeps tinkering with his pitch mix, so I feel he'll never focus on his best offerings and be the best pitcher he can be. He continues to remain a disappointment.
Tatsuya Imai: Imai's struggles are glaring and aren't just limited to lefties. He has a 5.0 BB/9 against righties.
He's just fastball-slider, with no offering to get lefties out. Over his last three games, he introduced a splitter to help with lefties. He's been better over that time frame, with a 5.40 ERA (2.70 xFIP), 1.35 WHIP and a 4.1 BB/9.
The splitter might be an answer against lefties, but the walks make him a drop.
Troy Melton: Meton has been able to keep a low 2.05 ERA because of his .155 BABIP. All the ERA estimators, stuff models and projections put him around a 4.50 ERA pitcher.
Zack Wheeler: Even though Wheeler has a large split, his K-BB% against lefties is higher than most of the values the other pitchers have against righties.
