So point them out. Like I said I can clearly remember 2 plays where I said that was a bad play.
The thing about these defensive metrics is that we have no clue how they are claculated. We don't see spread charts and percentages of likely balls to be caught by an average left fielder. Everyone just closes their eyes and treats them like the gospel.
Offensive stats are awesome. Less subjectivity.
Offensive stats use the same weighted runs formula as defensive stats do.
As far as %'s of balls caught and whatnot. Let's look at what Statcast has to say about fly balls caught by some LF's this year.
5 Star Ranking Breakdown:
5 Star: 0 - 25%, 4 Star: 26 - 50%, 3 Star: 51 - 75%, 2 Star: 76 - 90%, 1 Star: 91 - 95%
Duvall: 0/2 Five Stars - 4/6 four Stars - 3/4 Three Stars - 4/5 Two Stars - 7/7 - One Star
Kemp: 0/4 Five Stars - 0/4 four Stars - 1/2 Three Stars - 2/2 Two Stars - 6/6 - One Star
Melky: 0/8 Five Stars - 0/0 four Stars - 1/6 Three Stars - 4/4 Two Stars - 12/12 - One Star
Upton: 0/2 Five Stars - 2/5 four Stars - 2/3 Three Stars - 7/7 Two Stars - 5/5 - One Star
Gardner: 0/4 Five Stars - 3/4 four Stars - 2/2 Three Stars - 4/4 Two Stars - 4/4 - One Star
Tomas: 0/4 Five Stars - 0/1 four Stars - 0/0 Three Stars - 3/7 Two Stars - 3/4 - One Star
Now here are their DRS numbers
Duvall: +2
Kemp: -3
Melky: -2
Upton: +4
Gardner: +5
Tomas: -5
A couple of things of note. Statcats numbers are just on flyballs caught. DRS numbers include cutting balls off in the gap and ranks a players arm as well. And the main difference between those left fielders considered good and those who are bad lie in the balls that are considered 3 and 4 Stars. So balls that are caught 25-75% of the time. Good outfielders will generally have caught some in the 26-50% range and catch over 50% in the 50-75% range. Those who are bad don't catch any in the 26-50% range and usually half or less in the 50-75% range.
You may disagree that only a handful of plays can determine who a good fielder or bad fielder is. But you have to realize that is also just takes a few hits to determine who a good or bad hitter is as well.