Seth Lugo Is Having The Worst Stretch Of His Career, & His Fastball Is At The Center Of His Collapse

[Yirsandy Rodríguez]

Image courtesy of Kiyoshi Mio-Imagn Images

It's hard to find a worse decline than Seth Lugo’s since July: in 17 starts, he has the highest ERA (6.24) among qualified starters, the third-worst xFIP (4.78), and the second-lowest LOB% (61.1). That is only a summarized part of the problem. The worst part is that Lugo has become increasingly predictable. His strikeout rate has fallen to 6.3 K/9 — the second-worst mark in the ranking — and his pitches are generating the lowest chase rate from opposing hitters when he throws them outside the strike zone.

The problem is not hidden in the repertoire of the 36-year-old veteran right-hander. Lugo’s fastball and breaking ball have fallen from the 96th percentile in 2024 to the 11th and 1st percentiles, respectively. Most of the metrics, such as Chase%, Whiff%, xBA and xSLG, have fallen to career-worst percentiles for Lugo and are also among the worst marks in the major leagues.

The decline in impact has been terrible, but there is no bigger problem here than the way hitters are crushing Lugo’s four-seam fastball. In 86 plate appearances, they are hitting .416 with a .701 slugging percentage. The result becomes much more concerning when we see that this is not a complete decline. When comparing some of Lugo’s metrics with last season, when he limited hitters to a .238 BA and .495 SLG against his four-seam fastball, there are some surprising differences: he has a higher Whiff Rate (15.7% vs. 14.6%), he is generating a lower Perfect Contact rate (26% vs. 38%), and his average velocity remains at 91.7 mph.

There is also no drastic change in his IVB (15.2”), although it is below his own level from previous years and 0.4 inches below average. In fact, the Horizontal Break (8.8”) is the major change in 2026: +1.4” from 2025 and +2.1” from 2024.

If we had not seen the results of those 86 plate appearances, much of this analysis would lead us to think that Lugo’s four-seamer is not failing because it has lost everything that once made it work. In a way, part of the reality is the opposite. At 91.7 mph, Lugo has less velocity and less ride than he did in 2022–23, but he is now generating more horizontal movement. That said, what might have indicated some improvement has resulted in the exact opposite.

We usually look for trends that help us understand what is happening in each pitcher-batter matchup and, in the case of pitchers, how they are trying to attack and how their weapons are being answered. Lugo’s case is largely the result of many fastballs that failed to put him in control of the at-bat. It has not been as deficient within the matchup as the final results make it appear.

This chart allows us to answer most of our questions about his fastball. Literally, opponents are getting to it throughout the strike zone, which has led Lugo to reduce its usage by nearly 4.0% from June to now. The chart on the left shows all at-bats, while the middle one shows matchups against left-handed hitters and the next one against right-handed hitters.

As you can see, left-handed hitters have been unstoppable in the strike zone, especially when they hit pitches from the middle of the zone and above. Right-handed hitters have been more limited, but they have produced good results when they connect with pitches high in the middle of the zone and outside the strike zone. From June to now, no qualified pitcher with at least 200 four-seam fastballs thrown has allowed more damage than Lugo.

Name	Pitches	AVG	OBP	SLG	OPS	ISO	BABIP	wOBA	wRC+
Seth Lugo	227	.429	.489	.833	1.323	.405	.516	.550	272
Jack Perkins	359	.329	.455	.772	1.227	.443	.327	.503	238
Carson Whisenhunt	215	.436	.556	.641	1.197	.205	.471	.504	232
Kyle Finnegan	276	.400	.463	.686	1.148	.286	.434	.486	225
Zack Littell	245	.321	.397	.786	1.183	.464	.278	.491	223
Luis Medina	208	.413	.517	.609	1.126	.196	.581	.482	222
Zac Gallen	212	.400	.433	.709	1.142	.309	.367	.481	216
Spencer Arrighetti	277	.346	.379	.769	1.149	.423	.324	.471	215
Merrill Kelly	431	.321	.433	.718	1.151	.397	.254	.475	212
Jeffrey Springs	509	.340	.446	.660	1.107	.321	.355	.465	212

There are results that seem absurd, such as the .516 BABIP, the remarkable 1.323 OPS allowed, and the 272 wRC+. His opponents’ in-zone contact rate against Lugo during that span is 95.5%, the highest he has allowed in any month or stretch of the first or second half of a season in his entire career.

All of the trends you see there continue to rise. Lugo has allowed a .454 BA and an average exit velocity above 93 mph since July. We know this decline in performance is unprecedented, but the decline of his four-seam fastball began last season.

Since then, Lugo has thrown 1,662 four-seam fastballs and has never been able to record two consecutive swings and misses against any opponent. Regardless of everything we have analyzed here, that says a lot about what Lugo himself must be feeling and where his confidence stands every time he has to throw a fastball.

There is very little time left this season to change this story, so Lugo will have to think about how he is going to make his adjustments while the Royals also explore how much he can contribute to their rotation in the future.

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