kieckeredinthehead said:
All of the available data that we have - as unreliable as it is - suggests that Bogaerts hasn't been great, but there's very little chance that it's cost the team more than a fraction of a game. That's from the conversations here, from sources and anonymous scouts/coaches, and from the available defensive metrics. It's amazing how much argument there's been over something about which there's actually very little disagreement.
Thanks for setting up the poll, Kiecker. the disagreements played a small role in the formation of the poll; the idea to generate the poll arose out of the discussion of how best to measure what Xander has done so far this season.
kieckeredinthehead said:
I'm sure some of the votes are informed by UZR, so it's a bit circular. Nevertheless, estimates here appear to be more stable than UZR.
Research into crowdsourcing suggests that voting crowds who are informed by expert opinions (particular contradicting ones) provide more reliable and accurate estimates. It's controversial, but even studies that have not found this effect did not find that the estimates were poorer.
wade boggs chicken dinner said:
You have the wrong circularity. People think he is below-average; that is why they picked cost 0-5 runs. For instance, I'm sure there aren't a lot votes that said he was below average but had him saving runs on whole.
I wouldn't call it a circularity. The first question creates a priming effect where people are biased to answer the second question on the basis of the first. Still, you are right that this creates a confound. It probably would've been better to ask people to pick a number of runs that Xander has saved (with negative values being runs he has given up). I'm not sure the estimates would be less stable though, because most would probably select somewhere between 0 and -5 runs.
smastroyin said:
I think the problem with this poll is that the wisdom of crowds relies on a large crowd without bias. Since most of the people interested in this subject are heavily invested in one side of the debate, you may not actually get the fair view you are looking for.
I'm also not sure why this drum needs to be beaten so loudly for a 21 year old after a month or so of play in the majors. We need things to talk about but why is it always "this player really sucks at baseball because I'm pissed at the team right now and he made this bad play that I remember."
As for the magnitude of how bad he has been. The Red Sox as a team have a .312 BABIP allowed this year and a collective FIP/xFIP of 3.43/3.66 versus their actual ERA of 3.68. This doesn't really indicate to me that the Red Sox problem this year is with fielding. But let's compare to last year. Last year they had a .294 BABIP allowed and 3.89/3.84 vs. 3.79. So last year they were better than expected whereas this year they are about where you would expect. (The FIP/xFIP difference this year is largely due to a very low 8.4% HR/FB ratio, which Xander, JBJ, and everyone else on the field have little control over).
At the end of the day, when comparing to average, we probably need to think about average instead of the 2013 team, who were very good at least on a cursory look.
Scale is also a problem. The Red Sox have given up 158 runs this year, in 337.2 innings. They have 318 strikeouts, second in the league. That means they've recorded 695 outs in other ways, while allowing 303 non-HR hits. The idea that he's responsible for allowing 5-10 runs (or more!) doesn't make a lot of sense within these numbers.
A lot of good points here. You are right that crowdsourcing works with large numbers of independent votes (~2000). However, there are resampling techniques that can measure the level of bias and its effect on the central tendency. If you want, I could bootstrap the results after 100 votes, and establish confidence intervals for the bins. It's unfortunate that the selections here aren't continuous, but it doesn't really matter much for bootstrapping.
I'm not really complaining, nor do I think most non-plympton people are. Bogaerts has contributed to the team as an ML starting shortstop and I (along with many) are excited to see how he grows.The poll really stemmed out of how to think about measuring what bogaerts has done. As absinthe suggests, this type of poll could be a way of checking our own reality as the season progresses.
Regarding how to evaluate the team's defense, I completely agree with you. Our April woes had more to do with bad luck offensively (injuries, problems with RISP, baserunning blunders) than anything else.