While watching the Mets pound on the Cubs yesterday, I noticed that David Wright still has a walk rate (BB%) higher than his strikeout rate (K%). If Wright managed to continue this trend through the end of the season it would be the first time in his career he achieved such a feat.

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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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UPDATED

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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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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Mets first baseman Ike Davis has seen the number of fastballs thrown to him drop significantly since his rookie season in 2010. In that year, 57% of the pitches thrown to Davis were some type of fastball. So far in 2012? Only 51%. There have been only 30 seasons between 2007 and 2011 where a hitter with more than 100 plate appearances saw a lower percentage of fastballs in a season than Ike this year — and only five where a player accumulated more than 500 plate appearances.

Clearly pitchers are adjusting to Davis, altering their approach based upon Davis’ perceived offensive strengths and weaknesses. This got me thinking about the extent to which major league pitchers adjust to hitters from year to year. Was this change significant, or more common based on the normal adjustments hitters can expect to see from year to year.

As a first cut, I decided to look at changes in the pitch types that batters faced in consecutive years. Throwing hitters a different mix of pitches (i.e. fastballs, curveballs, sliders, etc.) is just one way the league can adjust. Pitchers can alter location, sequence and speed. However, the data was more readily available for pitch types, so the choice was made to focus there first. Read the rest of this entry »

After suffering through an abysmal 2011 season, White Sox designated hitter Adam Dunn is off to a fantastic start this year.

Last season, the 31-year-old Dunn put up a career-low .266 weighted on-base average (wOBA), or 59 wRC+, in nearly 500 plate appearances. His on-base percentage — which normally was a strength for the slugger — was .292, or 62 points below his previous career low when he was 23. Most disturbing was the sudden disappearance of his power. Dunn has always been a high-strikeout, high-walk, high-slugging player. But last year, Dunn posted an isolated power of only .118. To put that into perspective, consider this: Dunn’s ISO was only two points higher than Nyjer Morgan’s (.116). Dunn also saw his HR/FB ratio drop to 9.6% in a hitter- and home-run-friendly park. His previous career-low was 17.8%, all the way back in 2002.

But now? Well, we’re seeing the old Adam Dunn. Through May 7, he has managed a .394 wOBA, which is fueled by a .364 OBP, .321 ISO and a 28.1% HR/FB. And both the ISO and HR/FB numbers are better than his career highs. The obvious question is whether these numbers are sustainable. Given how quickly outcomes like BB% and HR/FB stabilize, there’s a good chance that Dunn’s end-of-season numbers could be similar to what they are today. The question I have is what is Dunn doing differently? To get a better handle on this, I took a look at Dunn’s performance on specific pitches in different locations.

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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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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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During Monday’s Baseball Today Podcast, Eric Karabell and Mark Simon were discussing a listener’s question regarding who has made the most outs per plate appearance in a single season. The idea here being you want to not only look at hitters with low on-base averages (OBA/OBP), but also include the extra outs generated by grounding into double plays*.

It is an interesting trivia question. And since I am pretty well jammed up this week working on multiple projects and deadlines I thought this would be a nice, quick topic to tackle.

To calculate this I looked at all players with >= 300 plate appearances in a season since 1950. I then calculated the outs they generated–((AB+BB+HBP+SF)-(H+BB+HBP))–which is really just reverse OBP, and added in the total number of double plays that they grounded into for the season (GDP). I then took this number and divided it by their plate appearances for the season to get their Total Outs Generated per PA.

Here are your top 10 and bottom 10 since 1950:

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While velocity isn’t everything when it comes to being a successful major league starting pitcher, it’s surely a large part of the story. Starting pitchers who have a higher velocity — particularly on their four-seam fastballs — tend to have higher strikeout rates and induce weaker contact from opposing batters. And pitchers who can limit balls in play through strikeouts, tend to have lower earned run averages. Of course, not every major-league starter can sport a blazing fastball. A number of starting pitchers have not only survived, but they’ve thrived during seasons where their velocity was significantly lower than league-average.

Which brings us to the case of Oakland Athletics left-hander, Tom Milone. After starting five games as a 24-year-old for the Nationals last season, Milone was shipped out as part of the deal that sent Oakland’s Gio Gonzalez to Washington. Milone, now 25, has worked his way into the Athletics’ rotation this season — this despite an underwhelming fastball. Generally, Milone’s four-seam fastball (a pitch he throws about 54% of the time) has averaged less than 88 mph. For some perspective: In the past three seasons, major-league starters have averaged 91 mph on the four-seamer.

What are the odds that Milone can perform above league average this season, given the lack of zip on his fastball? To answer this, I looked at some similar pitchers who have played during the Pitch FX era (2007-present). Read the rest of this entry »