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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Carl Crawford, Adam Dunn, and Jayson Werth signed large free agent contracts with new teams last offseason, and each were unequivocal disappointments in 2011 with their new club. This phenomenon is not limited to free agents. In recent memory, several highly touted prospects have been traded and not lived up to expectations with their new teams: Justin Smoak, Brett Wallace, and Kyle Drabek, to name a few.

Whenever a player changes teams and fails to live up to expectations, I find myself wondering, “Did his old team see this coming?” In these specific examples, we may never know, but we do know that teams have internal information which creates an advantage in personnel decisions. While this advantage may never completely go away, there is evidence to suggest that it’s starting to disappear.

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Fernando Rodney has three saves and a win so far this season. Fernando Rodney has gotten eight outs so far this season. As strange as it may first seem for a late-inning reliever to have four decisions with so few batters faced, it’s business as usual in Tampa Bay. Here’s a box score that is fairly typical for the Rays:

It certainly appears that the Rays are micro-managing their bullpen. Perhaps the aim is to gain the platoon advantage in as many situations as possible — teams do that all the time. But which ones are doing it most often?

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This past Tuesday on MLB Network’s Clubhouse Confidential, I predicted that Mets first basemen Ike Davis would be the breakout player in MLB this coming season. Yes, it was a bit of a homer pick, but I had solid reasoning to back it up. In his first 754 plate appearances in the big leagues, Davis put up an OBP of .355, a SLG of .457, and a wOBA of .352 all while playing in the pitcher-friendly Citi Field. That translates to a 121 wRC+, not bad considering only six other players 24 years old or younger have ever matched or exceeded that total over their first 800 plate appearances.

While watching Davis go 0-for-4 with two strike outs in yesterday’s opener I noticed something interesting: the Braves only threw Davis one fastball out of 18 total pitches. Not only that, but 41% of those pitches where thrown low and away, with Davis striking out twice on pitches in that area.

We can’t read too much into performance metrics in the early part of the season, especially after the first game, but the strategy executed by the Braves yesterday is consistent with the book on Ike, and may have provided a preview of what the young slugger will see throughout the year.

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Most readers understand that the phrase Three True Outcomes (TTO) refers to walks, strike outs and home runs. In an August 2000 article at Baseball Prospectus, Rany Jazayerli noted that these outcomes are “true” in the sense that they are largely independent of all things — outside that mano-a-mano moment between the batter and the pitcher:

Together, the Three True Outcomes distill the game to its essence, the battle of pitcher against hitter, free from the distractions of the defense, the distortion of foot speed or the corruption of managerial tactics like the bunt and his wicked brother, the hit-and-run.

None of the three true outcomes are significantly impacted by what happens outside the batters box*. Therefore, players with a higher percentage of plate appearances that end in TTOs have their fate largely decided at the plate. The poster child for the TTO? Rob Deer. His career TTO percentage ((HR+SO+BB)/(PA)) was 49.7%.

I thought it’d be interesting to look at how TTO players have evolved over time and what accounts for their successes and failures.

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Part two of a two-part series.

In Part I of this series, I dove into some Pitch F/X data to try and tease out how Adrian Gonzalez changed his approach after leaving San Diego in 2011. Overall, pitchers did not appear to adjust their approach to Gonzalez, evidenced by the fact that the distribution of pitches by location in 2011 was almost identical  to 2010. Gonzalez, however, did seem to alter his approach by altering what pitches he offered at, most notably swinging at more balls away and up in the zone. The change in his swing distribution combined with the change in his performance seemed consistent with the theory that the slugger was purposefully being more aggressive on pitches outside of the strike zone in an effort to take advantage of the Green Monster at Fenway Park. But to get a firmer handle on this we needed to split out Gonzalez’s data by home versus away.

That is the focus of this article.

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This is the first of a two-part series on Adrian Gonzalez’s evolution as a hitter.

Writing for ESPN.com last year, Dave Cameron suggested that then-newly-acquired slugger Adrian Gonzalez was displaying a new approach at the plate in Boston. Cameron pointed out that, as of May 14, Gonzalez had significantly reduced his walk percentage (BB%) and increased contact on pitches outside the strike zone (O-Contact %). Like 2010, Gonzalez was back to swinging at more pitches, but was making contact on roughly 85% of his swings. That was a huge jump from his carreer average at the time.

Since we’re on the cusp of a new season, I thought it’d be interesting to revisit Gonzalez’s 2011 to see if those early season trends held for the entire year. Overall, Gonzalez put up a .406 wOBA in 2011, versus a .378 with the Padres in 2010. The smooth-swinging first basemen got on base more often and also slugged for a higher percentage —though his ISO numbers were nearly identical. So the question is this: Was his 2011 success due to a different approach?

To figure that out, I created a series of heat maps based on Pitch F/X data that compare Gonzalez’s performances in 2011 and 2010. For the first part of this series, I’m only focusing on his overall performance. In the second part, I’ll take a deeper look and mine his home-road splits.

The first thing we need to check on is whether opposing pitchers took a different approach with Gonzalez after his move to Boston. As the data suggest, pitchers didn’t appear to approach Gonzalez all that differently:

There are some small changes in certain zones, but pitchers were pretty consistent with Gonzalez. Even if you break out fastballs from off-speed pitches, the percentages are basically the same by zone between 2010 and 2011.

Despite the season-to-season similarities, though, we see striking differences in the slugger’s approach in different zones.

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What do these fellow batsmen have in common?

• Adrian Gonzalez
• Matt Kemp
• Emilio Bonifacio
• Michael Bourn
• Michael Young

Well, probably a lot, seeing as how they all share a profession, but today let us examine a particularly unique distinction: The fact that they collectively represent the top five BABIPs of the 2011 MLB season.

Let’s find out how much was luck and how much was repeatable.

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