Archive for Featured

Review: Jeff Zimmerman’s 2025 BOLD Predictions


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It’s time to review my preseason BOLD predictions.

1. Cristopher Sánchez will be a top-3 starting pitcher.

He didn’t quite make it to the top three but ended up sixth according to our player rater. I’ll take it as a hit.

Batting: 1.000 Read the rest of this entry »


Mining the News (10/13/25)


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American League

Angels

Logan O’Hoppe is going to be the team’s main catcher after struggling in 2025.

To this day, the Angels view O’Hoppe as their guy, said Angels GM Perry Minasian. When he comes into spring training next season, he won’t need to earn the job.

“Logan had a tough year, there’s no sugarcoating that,” Minasian said. “But yes, we believe Logan can catch. It’s a really tough position. To break in a young catcher takes time. I’m expecting a better Logan O’Hoppe.”

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Mining the News (10/8/25)


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Note: There was so many “season in review” pieces that came out I’m still working through them. I’ve got at least one more Mining the News from end-of-season comments.

• NBP’s Takahiro Norimoto could sign with an MLB team.

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Mining the News (10/7/25)


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Other

Batters rarely add power once in the majors and start declining due to better early-career training.

Position players are not becoming stronger in their late 20s, as conventional wisdom suggests. Bat speed and exit velocity are not immune to aging like so many other movement- and speed-based skills in the sport (like pitching velocity).

When players arrive in the major leagues, many of their underlying skills are nearly as good as they will ever be – at least since we’ve had the ability to measure them in the Statcast era.

Driveline director of hitting Tanner Stokey noted that those skills’ aging curves might have been different years ago – perhaps more players did grow into strength and bat speed – but it is a different game in the modern era.

“You just assume players are the most physically gifted they’ve been – they have all the resources in the weight room, the nutrition side, the sleep, recovery side, right? It’s very different than it was back in the day,” Stokey noted. “That stuff is pretty optimized compared to where it was 20, 30, 40 years ago.

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Lessons Learned: Season in Review


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This past season was one of my worst ever. And about halfway through it, the outcome looked worse than the final results. I was able to focus on a few leagues and salvaged my bankroll. Here are some of the lessons I learned. Read the rest of this entry »


Hitters Who Played Through a 2025 Injury


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With the regular season over, it’s time to find out how hitters performed who didn’t let an injury heal and played through the pain. Whether these hitters cause permanent damage to their bodies or pick up bad habits, they continue to underperform their next season’s projections. Besides collecting the names myself, I’ve asked for some help (article) for this past season’s list.

First, here is a look at how 2024 hitters performed compared to their Steamer projections.

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2025 End Of Season Closer Report


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A few days ago, I asked for help to double-check this season’s initial closers (full 2024 edition).

Here are the results, starting with the initial closers and their performance.

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Chad’s Mistakes Made, Lessons Learned

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Chatting with Jake Mailhot about our plans for the off-season, he mentioned something his kid talked about: learning from her mistakes. First of all, that’s some A-plus parenting, Jake. But then Jake took it a step further and suggested that if his daughter could learn from her mistakes, so could we. So here are five numbers that represent mistakes I made this year and the lessons I learned.

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The Balance Between Called Strikes and Chase

Sep 15, 2025; Tampa, Florida, USA; Toronto Blue Jays pitcher Brendon Little (54) throws a pitch against the Tampa Bay Rays in the sixth inning at George M. Steinbrenner Field.
Credit: Nathan Ray Seebeck-Imagn Images

In early June, Alex Chamberlain graced us with a FanGraphs article about Brendon Little and a new concept called, “Implied Miss Distance”. Chamberlain, along with Baseball Prospectus writer/researcher Stephen Sutton-Brown, have done some great work utilizing Statcast bat tracking data, giving readers a new perspective on something like a swing and miss. But, back in early July, nearly a month after Chamberlain wrote about Little’s amazing knuckle-curve and it’s ability to make hitters whiff so hard that the outfield flag flutters, hitters stopped chasing the pitch. They were tired of looking silly and would no longer budge, allowing us to imply nothing:

A Rolling Line Chart of Brendon Little's O-Swing% 2025

If it wasn’t for Chamberlain’s article, I wouldn’t have known about Little or his knuckle-curve. But that’s why FanGraphs is the best, and when I recently watched the Blue Jays and their relievers’ deteriorating August WHIP, I heard the broadcasters mention Little’s falling O-Swing, or chase, rate.

If you only focused on Little’s knuckle-curve and the damage hitters have done to it in each month of the season, as you see in the table below, you wouldn’t think twice about the pitch’s performance:

Little’s Knuckle Curve by Month 2025
Month KC Total Pitches KC% wOBA
Mar/Apr 96 218 44.0% .194
May 111 229 48.5% .176
Jun 119 243 49.0% .212
Jul 103 193 53.4% .192
Aug 76 193 39.4% .146
Sep/Oct 51 119 42.9% .257

Among pitchers who have thrown at least 100 knuckle curves in any of the last five seasons, Little’s 2025 wOBA of .188 is a fringe top 20 (25th) out of nearly 200 pitchers. Last season, Little got even closer to the top 20 mark (23rd) with a .186 wOBA on the pitch. But the broadcast never said anything about Little getting hit; they were focused on the lack of chase and, therefore, an increased BB%:

A rolling chart of Brendon Little's Chase%/BB% 2025

The chart above includes all of Little’s pitches. By isolating the O-Swing% to only his knuckle-curve, we can see that this overall drop in hitters’ chasing after Little’s offerings wasn’t solely because of them spitting at that specific pitch:

A rolling chart of Brendon Little's Knuckle-Curve Chase% 2025

Thanks to the incredible addition of the Pitch-Type Split Leaderboard by the FanGraphs web team, we can now view the averages of individual pitches with ease. In 2025, among all pitchers who have thrown at least 10 knuckle curves, the league average O-Swing% currently sits at 35.5%. Little’s mark on the season is 36.5%. Rolling averages are different from season averages, and when Little’s chase rate rolling average dipped, so did the chase rolling average of his two other pitches:

A rolling chart of Brendon Little's Individual Pitch Chase% 2025

Chart 4 – Rolling KC, FC, SI Chase% Comps

The straight red line indicates times when Little stopped throwing his cutter. It’s interesting to see how the line stopped running horizontally around the same time his knuckle-curve was at its worst. Unfortunately, it didn’t fill the chased pitch gap, and that 40-50 game mark fell around early to mid-July when Little’s WHIP went upwards:

Brendon Little’s Monthly Splits (All Pitches)
Month KC% WHIP K-BB%
Mar/Apr 44.3 1.31 26.8
May 48.5 0.98 17.3
Jun 49.0 1.42 15.7
Jul 53.4 1.60 21.3
Aug 39.4 1.65 0.0
Sep/Oct 42.9 1.65 10.0

Hitters weren’t getting boosted wOBA’s from Little’s lack of chase, but the 1.65 WHIP  (5.97 eqiuv. ERA) meant they were hitting his other pitches and walking more. I’ve been rambling on about Little for more than a few paragraphs now, and you’re probably waiting for the point. The point? The point is, pitchers need to adjust when a pitch that used to be chased no longer gets chased. They know that. We know that. Yet, it’s difficult to keep track of on the fan side of things. Pitchers will go about adjusting in all sorts of ways.

In Little’s case, it was really just a blip. If you go back up to the graph showing individual pitch chase rates, you may notice that Little’s usage of the cutter, even if it wasn’t chased, allowed the chase rate on his knuckle-curve to jump back up. Hitters did a great job of laying off Little’s knuckle-curve from around games 30 to 70, but excellence is when a pitcher can adjust in the moment to hitters. That’s robotic. So, let’s!…get!…robotic! For the remainder of this article, I’ll present a detection system that can run daily to capture when a pitcher’s most used fastball and most used secondary are in good or bad rhythm using individual pitch plate discipline metrics. Here’s an example from Little’s 40 to 80 game span:

Categorizing Brendon Little’s Plate Discipline Balance
Game Number Rolling_CStr%_SI Rolling_Chase%_KC Performance
41-50 26.8 23.4 Ok (Adjusting)
51-60 21.1 25.8 Bad
61-73 16.9 21.8 Bad
SI Median CStr% = 24.5%
KC Median Chase% = 26.8%

The table is just a summary of what you see in Chart 4 above, but it’s designed to be placed in an automated system. If chase is up on one pitch and called strike is up on another, that’s good. If both pitches are falling to generate either chase or called strikes, well, that’s bad. Categorizing the balance between his sinker’s called strike rate and his knuckle-curve’s chase rate is as simple as creating rule-based logic:

conditions = [
(final_df['Rolling_Chase%']-3 > final_df['smart_median_chase']) & (final_df['Rolling_CStr%']-3 > final_df['smart_median_cstr']),
(final_df['Rolling_Chase%'] <= final_df['smart_median_chase']) & (final_df['Rolling_CStr%'] >= final_df['smart_median_cstr']),
(final_df['Rolling_Chase%']+3 < final_df['smart_median_chase']) & (final_df['Rolling_CStr%']+3 < final_df['smart_median_cstr']), (final_df['Rolling_Chase%'] >= final_df['smart_median_chase']) & (final_df['Rolling_CStr%'] <= final_df['smart_median_cstr'])
]
# Define the corresponding categories
categories = [
'Excellent',
'Ok (Adjusting)',
'Bad',
'Ok (Adjusting)'
]

Using the pitcher’s median values allows the categorization to detect improvements by each individual. I’m using “smart” medians to call the league median if a player has a zero value. That happens when they haven’t generated any chase or called strikes. If we use Brendon Little’s game logs to isolate his performance during those game periods from the table above, we see some pattern in a very small sample:

Brendon Little’s Overall Performance in Small Samples
Game Number WHIP K-BB%
41-50 0.91 32.3%
51-60 2.10 0.0%
61-73 1.33 15.4%

Little was at his best when he was in decent balance. This is the type of tracking that could be useful when streaming pitchers or looking for hot relievers. To test this out on a grander scale, I built a dataset that includes data from the last two months. This keeps the sample limited to more recent performance. Furthermore, I limited the data to only pitchers with more than 60 total pitches thrown in that time. Then, I took each pitcher’s most utilized fastball by pitch percentage and used it to calculate their called strike rate. I did the same with each pitcher’s most utilized offspeed, or non-fastball, pitch and used it to calculate their chase rate. I then calculated each pitch’s 15-game rolling rate, called strike for fastballs and chase for non-fastballs, and labelled their performance balance. Finally, I counted the number of days in which a player has been either good (balanced) or bad (unbalanced) and found the current status of players in both groups:

Players With Excellent Balance
Player Rolling CStr% Rolling Chase% Days of Excellence
Emilio Pagán 14.4 31.7 5
Dennis Santana 32.1 24.3 2
Tanner Scott 14.0 22.3 2
Jared Koenig 32.2 22.0 3
Yerry De los Santos 21.7 20.0 2

Players With Poor Balance
Player Rolling_CStr% Rolling_Chase% Days of Poor Performance
David Robertson 7.7 12.9 -16
Carlos Hernández 0.0 4.0 -2
Trey Yesavage 23.1 16.2 -1
Joe Rock 31.8 18.5 -1
Andrew Hoffmann 12.8 0.0 -2

The results focus on a pitcher’s most recent stretch. For example, Emilio Pagán has had one of his best K-BB% (22.4%) marks of his career this season, and in his last five games, it’s been even better (26.3%). He’s had recent success thanks to his four-seam and splitter working in unison.

Is there more to do? Always. I’ve only compared fastball called strike rates with offspeed chase rates, but all of these plate discipline metrics could be compared for balance. For example, it may be better to have a balanced swinging strike rate and chase rate. But, fundamental to this analysis is the assumption that it’s hard to get anywhere without a fastball and offspeed pitch that work well together. Does it mean anything? Is the balance even predictive of future success? Maybe, maybe not. What it certainly can do, as I believe I’ve exemplified here, is explain a pitcher’s success or lack thereof. If you are interested in doing this analysis on your own without spending hours calling and pinging pybaseball’s API, you can view pitch-specific plate discipline metrics on our new and totally awesome Pitch-Type Splits Leaderboards. Stay balanced, stay cool.


Mining the News (9/26/25)


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Note: Teams out of the playoffs are starting to drop end-of-season reports. I’m going to be behind for a couple of weeks catching up.

American League

Athletics

Zack Gelof had surgery on his shoulder.

Athletics second baseman Zack Gelof had successful surgery on his left shoulder to address an injury sustained earlier last week, the team announced Wednesday.

Dr. Neal ElAttrache performed an anterior labral-capsule repair in Los Angeles to address instability after Gelof’s injury in Pittsburgh on Sept. 19.

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