Posted by burnsy483 on 8/14/2013 9:17:00 AM (view original):
Posted by bad_luck on 8/13/2013 11:41:00 PM (view original):I'd argue Cabrera was slumping terribly. Which I guess brings the next point - can you "slump" in the field for an entire season? Again, Trout was considered GG quality last year, and this year, he's considered to be easily replaceable in the field.
Posted by trsnoke on 8/13/2013 11:38:00 PM (view original):I agree. If Miguel Cabrera had a slugging percentage of .350 for a couple hundred at bats, no one would consider SLG broken or unreliable.
it seems like there are a lot of those oddities but I wonder if it really happens as often as it seems or if those examples are just brought up a lot. I'm going to look at that at some point - offensive value for any given player can fluctuate year-to-year, so why not defense? Maybe defensive value doesn't fluctuate more than offensive value. It does seem like it does, though.
Has anyone looked at Trout play the field this year and said "Damn, what's wrong with him?" Maybe they have and I haven't heard it.
Why can't you slump in the field?
Everything I've read about fielding stats say that they don't normalize until you have a big enough sample. Like hitting stats.
You need 60 plate appearances for a hitter's K rate to be reliable. 120 for walk rate. 320 for SLG and 460 OBP. 910 (a year and a half for a starter!) for BA.
You really need three years for UZR.
Here's what Fangraphs says:
Since defensive statistics are still relatively new, they should not be taken as 100% dead accurate. Before drawing any conclusions about a player’s defense, look at a full three years of defensive data, drop the decimal points and take an average, and compare UZR scores with other defensive metrics (DRS, TZL, etc.). By taking a broader picture, you will help ensure that you’re not being over-confident or overstating a player’s defensive abilities.
In general, UZR scores can be broken down into the following tiers. This is a good shorthand way of evaluating a player’s defensive ability level:
|Gold Glove Caliber
Things to Remember:
? Beware of sample sizes! If a player only spent 50 innings at a position last season, it’d be a good idea not to draw too many conclusions from their UZR score over that time. Like with any defensive statistic, you should always use three years of UZR data before trying to draw any conclusions on the true talent level of a fielder.
? UZR uses Baseball Info Solutions (BIS) data in calculating its results. It’s important to note that this data is compiled by human scorers, which means that it likely includes some human error. Until FIELDF/x data gets released to the public, we are never going to have wholly accurate defensive data; human error is impossible to avoid when recording fielding locations by hand, no matter how meticulous the scorers. That said, BIS data is still the best, most accurate defensive data available at this time, so just be careful not to overstate claims of a player’s defensive prowess based solely on defensive stats.
? Since UZR is a counting statistic like RBIs or HRs, the more playing time a player accrues, the higher (or lower) their UZR will be. In order to compare players with different amounts of playing time, UZR can be scaled on a 150 game basis (UZR/150). If you want to compare a player with 90 games played to someone with 140, UZR/150 would be the way to do so.
? UZR is park-adjusted, meaning it adjusts for the fact that fielders have to deal with odd quirks in certain ballparks.