Let's wrap up this series - new Trailing 30 to post.
When you look at the worst by position, it's amazing how many teams have really bad hitters at each position. There are nine teams whose centerfielders have an on-base percentage of .302 or less. That's 30% of teams, and it's really bad, for what is probably the most important offensive statistic. (I'll get around explaining why one of these days for those of you who are skeptics). So guys like Mike Trout and Andrew McCutchen and Carlos Gomez are really exceptions to the rule.
As for the other end of the spectrum, there are six teams (Mets, Braves, Twins, Giants, Marlins, and Astros) who've gotten almost nothing in terms of offense from their center fielders. The Mets have settled on Juan Lagares, who's been decent and is pulling up the overall statistics. For the Braves, BJ Upton was probably the worst position player in baseball for April and May but showed signs of life starting in June before getting hurt; he's back in the lineup now. The Twins have finally thrown in the towel on rookie Aaron Hicks, sending him and his .192 BA, .259 OBP, and .338 SLG to AAA on Thursday. The Giants have had a black hole in center since Angel Pagan got hurt, but they've had great fielding at a key defensive position all season. So it's between the Houston and Miami...pretty close. The Astros CFs are 27th in BA, 28th in OBP, 30th in SLG. Marlins are 28th, 30th, and 27th. Both have been below-average defensively--Houston by a lot, depending on your choice of defensive metrics. I'm going to go with the Astros, on the basis of two bonuses: First, they've hit fewer homers, struck out more, and walked less than Miami; and second, they're the only center fielders who have been successful at fewer than half of their stolen base attempts, swiping eight and getting caught a major league-leading ten times.