Digging Under Projections

When it comes to projections, I am and have been fairly confident and content with the offensive variety. Measuring offense is by no means a solved problem, but we have very good approximations and given the sample sizes and independent nature of offense, not only can we measure it well, but it stabilizes and projects well. Honestly, I think the most exciting front in offensive analysis is further enhancement of park factors, which actually is a pervasive effect and not limited solely to hitters.

Dave Allen touched on my crusade on the pitching front already. I am a big proponent of looking at pitchers on a per-pitch level. In addition to studying pitch types and their subsequent metrics (e.g. velocity), I advocate studying the result types of those pitches. A pitcher’s strikeout rate shows a strong correlation with his swinging strike rate, and little to no correlation with his called strike rate. Correlation does not imply causation, but swinging strike rate is one of my favorite one-stop metrics to glance at when looking for either breakout or regression candidates. When the strikeouts and missed bat rates are out of whack, I look for a change in the coming year.

Offense and pitching are not the only parts of projections, though. Here at FanGraphs you are given the chance to project defensive adequacy as well. That is a tricky issue. Defensive data is among the noisiest of all facets of the game. The standard rule of thumb is that three years of defensive data is needed in order to equal the confidence level of a single year of hitting data. Naturally then, a three-year weighted average of UZR data appears to be the best way to project next year’s figures, but beware of that simplicity.

The issue is that three years is a long time and it is important to note that how a player fields at age 25 is going to be different, perhaps vastly so, than at age 28, for one example. When you get into later seasons, it can be even more treacherous. Aging curve studies in fielding done so far seem to point to fielding being a skill that peaks early in a player’s career. When projecting defense, take care to remember that one year is a poor sample and that next year is probably going to be worse than the years prior.




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Matthew Carruth is a software engineer who has been fascinated with baseball statistics since age five. When not dissecting baseball, he is watching hockey or playing soccer.

5 Responses to “Digging Under Projections”

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  1. opisgod says:

    “A pitcher’s strikeout rate shows a strong correlation with his swinging strike rate, and little to no correlation with his called strike rate.”

    Well, unless your name is Greg Maddux or Roy Halladay…

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  2. NYRoyal says:

    I hope people will realize, as Matt does above, that defensive projections are inherently soft and mushy. Unfortunately, I’ve found that many people tend to treat the “best available stat” or “best available projection” in an area as if it were good enough, just because it is there. People want to be able to rely on a stat or projection. So when they see an attempt made at a defensive catching metric or a defensive projection (which are inherently extremely difficult to create with any degree of reliability), they jump on it. I fully expect many of my fellow sabrofiles to argue that Player X is likely going to be a better player than Player Y next year because he projects to be a little better defensively. Those projections are still too soft. But progress will happen. It will get better. But in the meantime, we shouldn’t pretend that a metric or projection is good just because it is the best currently available. If a metric doesn’t accurately describe a variable, or if a projection doesn’t reasonably project a variable, then they shouldn’t be relied upon. They should just be recognized, discussed, critiqued and improved upon.

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  3. Keith Ong says:

    While you are not in employment and do not hold any degree currently, I would advise that instead of reflecting any idle periods in your resume, keep yourself busy with studies during this period.

    Keith
    Easiest Degree

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  4. Keith O says:

    While you are out of job and without a degree yet, I would advise that instead of reflecting any idle periods in your resume, keep yourself busy with studies during this period.

    Ong Keith
    Easiest Degree To Get

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  5. Keith O. says:

    No absolute requirement to feel passive about our situation when our economy is not really good. I am sure everyone of us hope to be successful in life. Getting a degree would get us above the situation.

    Keith O.
    Easiest Degrees

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