Archive for Pitcher Aging Curves

Matt Moore and Others Likely to Lose Velocity

As some of you might remember from previous articles, velocity trends in July provide the strongest signal in terms of whether a pitcher is likely to experience “true” velocity loss over the course of a full season.

Yes, I know, we are more than halfway through August. However, between work, vacation, and Saber Seminar (which, if you didn’t attend you really missed out. You can still purchase posters and t-shirts, so get on that. It’s for a good cause) I’ve struggled to sit down and run the numbers. Better late than never.

Again, for reference, the table below breaks out the percent of pitchers who experience at least a 1 mph drop in their four-seam fastball velocity in a month relative to that same month a year ago and who also went on to finish the season down a full 1 mph. It also shows the relative risk and odds ratios for each month — meaning, the increased likelihood (or odds) that a pitcher will experience a true velocity loss at season’s end when compared to those pitchers that didn’t lose 1 mph in that month.

Month 1 mph Drop No 1 mph Drop Relative Risk Odds Ratios
April 38% 9% 4.2 6.2
May 47% 6% 7.8 13.9
June 55% 5% 11 23.2
July 56% 4% 14 30.6
August 53% 6% 8.8 17.7

So while the overall rate of velocity loss based on a loss in June and July look pretty even, the relative risk and odds ratios increase by a solid amount in July.

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Velocity Decline Trends for June, 2012-13

Well friends, we are now approaching that time of year where a significant drop in a pitcher’s velocity passes the 50% threshold in terms of signaling that they will finish the year down at least one full mph.

Month 1 mph Drop No 1 mph Drop Relative Risk
April 38% 9% 4.2
May 47% 6% 7.8
June 55% 5% 11.0
July 56% 4% 14.0
August 53% 6% 8.8

The table above breaks out the percent of pitchers who experience at least a 1 mph drop in their four-seam fastball velocity in a month relative to that same month a year ago and who also went on to finish the season down a full 1 mph. It also shows the relative risk — meaning, the increased likelihood that a pitcher will experience a true velocity loss at season’s end when compared to those pitchers that didn’t lose 1 mph in that month.

For example, pitchers that lost velocity in May finished the season down a full 1 mph 47% of the time, compared to just 6% that didn’t lose 1 mph in May — an increased likelihood of 7.8.

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Reliever Pitching Metric Correlations, Year-to-Year

A little over a year ago I published the results of a study that examined which metrics were most consistent on a year-to-year basis for starting pitchers. My colleague, Matt Klaassen, followed up and expanded on that study recently here at FanGraphs. Matt’s study also focused on starting pitchers–those with a minimum of 140 innings pitched in consecutive years.

Recently I was asked the following on Twitter:

I can’t speak specifically to what the common wisdom is Justin is referring to, but I can certainly run the correlations for relief pitchers and compare them to what I found for starters.

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Does an April Drop in Velocity Predict An Arm Injury?

Earlier this month I wrote about whether we should be concerned with when we see pitchers throwing slower in April, particularly with regards to CC Sabathia.

If we are trying to predict whether the pitcher has truly lost some zip on their fastball, the answer is somewhat. Pitchers who are down at least 1 mph compared to April of the previous year will go on to finish the season down at least 1 mph about 38% of the time. Essentially, they are over four times as likely to be truly losing velocity compared to those that are not down in April. However, the signal gains in strength as the season goes on. So, if a pitcher is down at least 1 mph in July compared to July of the previous year their likelihood of being down at season’s end jumps to 14 times more than pitchers that are not down in July.

But does being down in April predict an injury? This is something I had not yet investigated. Given the increased discussion about April velocity declines I thought I should take a quick look.

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CC Sabathia’s Velocity Is Definitely Worth Watching

Every year we hear stories about pitchers whose fastballs don’t seem to have the same life as last year. The most talked about are typically front-line starters that rely on their fastballs. In early 2013, the name that’s being discussed the most is Yankee ace CC Sabathia.

Throughout spring training, Sabathia’s velocity has been a point of concern. Coming off of elbow surgery during the offseason, Sabathia’s first regular season start did nothing to quell that concern. As The Star-Ledger’s Andy McCullough notes:

Sabathia’s fastball topped out at 91.7 mph on Monday, according to Pitch f/x data from Brooks Baseball. On Opening Day in 2012, his fastball hit 94.5 mph. On Opening Day in 2011, his fastball touched 94.7 mph.

(By the way, if you don’t read McCullough on a regular basis you are missing out.)

In the end, McCullough notes that while it’s reasonable to be concerned, Sabathia is likely to improve as the season wears on and has good enough secondary stuff to still be very good.

Overall McCullough is right, however, I think there is greater reason for concern than some may think.

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Felix Hernandez’s Velocity

Last week, the Seattle Mariners inked their ace, Felix Hernandez, to a $175 million extension for the next seven years. The dominating righty will be entering his age-27 season this year, meaning the contract will through his age-33 season. That is, unless, he injures his right elbow.

Embedded within Hernandez’s contract is a clause that gives the Mariners a club option for an eighth season — at a paltry $1 million — should Hernandez miss at least 130 consecutive days due to any kind of procedure to his right elbow. The Mariners negotiated this clause after some concern over what their doctors saw in the pitcher’s MRI.

Apparently, the club was reassured enough by their medical staff to sign the mammoth deal, even though the track record for long-term pitcher extensions isn’t the greatest. But how confident should the team be?
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Tim Lincecum Needs to Learn How to Pitch, Not Throw

Tim Lincecum‘s resume contains the following items: 2 time Cy Young award winner, 4 time All-Star and twice World Series Champion. With all the achievements over the last 5 seasons, he was relegated to a long relief once the Giants made the playoffs because he was no longer effective as a starter. Lincecum’s problem is he can no longer just throw the ball across the plate and hope a batter just swings and misses. If he wants any hope of returning to be the starter he once was, he now needs to learn how to pitch.

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Injury Chances for Strike-Throwers

In the Oct. 15 issue of ESPN the Magazine, Tim Kurkjian wrote this when talking about young pitchers with injury histories:

GM Billy Beane doesn’t require power, he wants outs without walks. Plus strike throwers generally have good mechanics that help prevent injury. Beane also isn’t afraid to go with young pitchers, what at least in theory are less likely than older ones to get injured.

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Velocity Trends and Pitchers to Watch in 2013

I’ve written quite a bit this year about pitcher aging — specifically, trends in velocity loss for pitchers. There are two general findings that I want to revisit today and apply to pitchers from 2012; the predictive power of velocity loss in July and end of season velocity, and the impact of losing velocity in one season on next season’s velocity.

First, a pitcher’s velocity will tend to vary throughout the year. Trying to get a read on whether a pitcher is having trouble velocity-wise during a season is difficult if you simply compare to last year’s overall velocity. So I compared a pitcher’s velocity in each month to their velocity the previous year in that same month and found that pitchers who lose at least 1 mph of velocity in July are 13.7 times more likely to finish the entire year down at least 1 mph.

Second, 91% of pitchers that do finish a season down at least 1 mph compared to the previous season will lose additional velocity the following season (average decline of 1.6 mph), with only 7% regaining some (but, likely, not all) of that velocity back.

With the close of the 2012 season, I checked back on how well July-over-July velocity trends predicted full season declines as well as which pitchers ended the season losing over 1 mph off of their fastball.

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When to Believe Velocity Gain

Last week, I wrote about some findings regarding in-season fastball velocity loss and how experiencing a loss in different months affects a pitcher’s chances of finishing a season with diminished pitch speed. The general takeaway was that June and July were the most telling months.

But what about velocity gain? We know that, generally speaking, pitchers lose velocity more than they gain it. So while velocity loss isn’t good, it’s to be expected — and starting pitchers seem to be able to deal with that loss better than relievers. Pitchers who can stave off velocity loss (year-over-year change between +/- .5 mph) perform even better. Moreover, if a pitcher gains at least 1 mph on their fastball in a season they are twice as likely to maintain some or all of that gain the following year.

Gaining velocity, while not a guarantee of better performance, is certainly a boon to a pitcher and his organization. But given that velocity varies for all sorts of reasons, when can a team have confidence that the increase they’re seeing is real and sustainable?

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At What Point Should We Worry About Velocity Loss?

I’ve written quite a bit this year on trends in pitcher aging, specifically velocity loss and gain. In the last iteration I focused on the odds of pitchers gaining velocity back after a season where their fastball dropped by at least 1 mph.

In that piece I listed a few pitchers to keep your eye on given that their velocity was down from 2011. In June, I wrote about CC Sabathia for ESPN and noted that the big lefty is likely beginning to “age”, as the odds are quite a bit higher that pitchers over the age of 30 do not gain their velocity back once they’ve lost it.

After thinking about it a while it occurred to me that there is of course the chance that these pitchers will gain their velocity back by the end of the year (as I noted in both pieces). We know that, generally speaking, pitchers gain velocity as the season goes on. Temperatures rise, and so too do fastball velocities. If this is the case I wondered at what point in the season we can say with greater certainty that a pitcher is throwing as hard as he is going to throw. Is there a particular month where a velocity decline is more likely to translate to or predict a full season velocity decline?
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Odds of Regaining Velocity, by Age

A number of pitchers with noticeably lower velocity this year either have landed on the disabled list or have had their seasons cut short due to injury. The Pirates’ Charlie Morton had Tommy John surgery (age 28, down 1.5 mph). The Tigers’ Doug Fister (age 28, down 1.1 mph) and the Blue Jays’ Brandon Morrow (age 27, down 1 mph) have both landed on the DL with oblique injuries. And the White Sox’ John Danks (age 27, down 1.5 mph) just started a stint on the DL due to elbow soreness.

Previously, I found that pitchers who lose at least 1 mph of velocity have over twice the odds of not throwing at least 40 innings in the subsequent year. This could simply be due to ineffectiveness, injury or both. A steep decline in velocity can create — or be a signal for — all sorts of problems. If a pitcher loses velocity simply due to a tired arm, they can increase their chance for injury by trying to pitch through it. Losing velocity also tends to make pitchers less effective over time. And once a pitcher loses velocity, the odds of regaining at least some of it the following year are very low (more on this below).

Today, I want to look at how age impacts the chances of regaining velocity for pitchers and then highlight some hurlers who fans should keep their eyes on this year and next year.

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How Secondary Pitch Usage Impacts Attrition


Last week I wrote about how losing velocity at different ages impacts a pitcher’s chance to throw 40 or fewer innings the next season (what I labeled “attrition”).

The overall finding was that losing velocity at any age increases the likelihood of attrition for pitchers, and that likelihood only increases with age. Overall, pitchers in the data set had a 29% chance of attrition between years one and two. If they lost at least 1 mph on their fastball, however, that rate jumped to 39%. Pitchers that didn’t lose at least 1 mph only had an 18% attrition rate–so half the odds. Starting at age 34, the attrition rate jumped to 50% and climbed for each age cohort until roughly age 39. (Thirty-eight-year-olds who lost velocity magically bucked the trend, attriting at about the same rate as all other pitchers.)

Eno Sarris asked me whether, as some have suggested, pitchers who relied on a change-up as their primary secondary pitch (such as a James Shields or Mark Buehrle) gained some kind of advantage, in terms of attrition. Do these pitchers have a lower chance of injury or ineffectiveness than someone who relies heavily on either a curveball (e.g. A.J. Burnett) or a slider (e.g. Ervin Santana)?

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Velocity Decline and Pitcher Attrition by Age

Note: The attrition data and chart was updated, showing a larger gap for just about all age cohorts

On May 26, the Twins released 33-year-old starter Jason Marquis. Considering how bad Twins pitchers have been this season, it really spoke to how bad Marquis’ numbers were to that point in the season.

In seven starts, Marquis posted a 8.47 ERA and a 7.25 FIP, numbers driven largely by a 7.5% strikeout rate, a 27.3% HR/FB and a sky-high .352 BABIP against. There was some speculation that, since Marquis has lost about 2 mph on his fastball since 2009, it was likely that he’d become more hittable — particularly at age 33.

This led to some discussion on Twitter about whether there was a greater likelihood that Marquis’ velocity drop at his age was more of an issue than if he had been a younger pitcher. It’s a legitimate question — whether diminished velocity has an impact, depending on age.

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Pitcher Aging Curves: Maintaining Velocity

Bill Petti published the first two parts of a series on pitcher aging. Bill’s first article focused on pitchers, in general, and the second was on the difference between starters and relievers. For the third installment, I’ll look at aging patterns for pitchers who maintain a relatively constant velocity from year-to-year.

From the previous articles, the average pitcher loses about 4 mph from their fastball from ages 21 to 38. In essence, most pitchers’ stats degrade as their fastball speed drops. Using the same methodology, I wanted to know how pitchers age when they don’t lose velocity on their pitches.

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Pitcher Aging Curves: Starters and Relievers

On Monday, Jeff Zimmerman and I launched our series of articles on pitcher aging. Readers should refer to introductory article, which includes general curves and a summary of the methodology. The general takeaway was that, as suspected, pitchers age differently than hitters. Generally, pitchers see their velocity peak in their early 20s and steadily decline by a full mile per hour by age 26. After that, velocity drops more sharply and continues a steep decline into a pitcher’s 30s.

Strikeout rates were tied to velocity, but not as closely after age 26. This indicates that those pitchers who survive into their late 20s and early 30s are less reliant on their velocity (and, most likely, their fastball) for strikeouts. A pitcher’s walk rate shows a some improvement through age 25 (due to starters), and then begins its decline.

In this article, I want to tease out some of the differences between starters and relievers.

Let’s quickly recap what the average aging curves look like for starters and relievers:

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Pitcher Aging Curves: Introduction

As on-field performance data has evolved, baseball enthusiasts have been spoiled with more precise measures of player performance. One area in particular is pitcher velocity. Whether through Baseball Info Solutions (BIS) or PITCHf/x, writers and researchers can now add a critical variable into their analysis that wasn’t readily available a decade ago.

Many readers of FanGraphs and Beyond the Box Score have seen Jeff Zimmerman‘s position player aging curves. After reviewing them, I started to pester Jeff to see if he considered similar curves for pitchers — specifically in the area of fastball velocity. I was curious about the general pattern of decline for fastball speed and how it impacts overall pitcher performance. Luckily, Jeff already had been thinking about this.

Today, Jeff and I are launching a multi-part series on pitcher aging curves, which is centered on fastball velocity. This introductory article will lay out the methodology we used and — of course — the initial baseline curves for all pitchers, as well as starters versus relievers.

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