When looking at the statistic of WAR on Fangraphs, it is clear that the positional adjustments they make are pretty arbitrary.
Since most players do not play all 162 games, it commonly occurs that they gain around 90-95% of these runs. For example, Pedroia would gain around .23 WAR if he played 150 games in a season at 2B, from the positional adjustment only.Since the offensive and defensive inputs into WAR don’t account for position played in any way, adding together wRAA and UZR without any sort of adjustment will severely underrate players at difficult defensive positions (think short stop, center field, catcher). It’s not that difficult to be a +5 defender at a position like first base, but it takes considerable talent to be a +5 defensive center fielder.
Here are the full FanGraphs positional adjustments used in WAR:
Catcher: +12.5 runs (all are per 162 defensive games)
First Base: -12.5 runs
Second Base: +2.5 runs
Third Base: +2.5 runs
Shortstop: +7.5 runs
Left Field: -7.5 runs
Center Field: +2.5 runs
Right Field: -7.5 runs
Designated Hitter: -17.5 runs
Based on this, a 2nd baseman having the same season as a 1st baseman (say, 3.0 WAR) will be 2.77 WAR to 1.84 WAR. Almost a full win (.93) difference.
Based on offensive values only, their positional adjustments are completely off. Take a look at this quick spreadsheet I made:
5 year Q - the number of qualified players at that position.
To reach average - The average was right around .330.
Based on OFFENSIVE only, it is clear that these adjustments are off. Third basemen do not deserve the same adjustment that second basemen receive, for one. In a purely offensive world, it would look something like this:
SS +20 runs
2B +12 runs
C +9 runs
CF +5 runs
3B +3 runs
LF -4 runs
RF -10 runs
DH -16 runs
1B -17 runs
I just multiplied by 10 to make the numbers look easier. What's important is the relationship between these numbers (proportionally), not the actual run amounts.
Obviously my results are very primitive and don't take many things into account. But the point I am making is clear. I don't understand how Fangraphs can just decide that one position is harder than another. Is this based on any fact? The amount of leaders in WAR from each position is pretty spread out, so my guess is no. Edit: what I mean by this is that UZR does not really favor a certain position, which would make that position "easier". For example, if 10 first basemen occupied the top 20 defenders, it would make sense to deduct them runs. However, this is certainly not the case, as only 2 are in the top 25 (Gonzalez and Teixeira).
So basically there could be three reasons that positional adjustments exist.
1) The simple fact that a replacement 1B is a better hitter than a replacement 2B. However, if this is the case, then it should be based on actual results, not just an arbitrary guess. It is obvious that a replacement 3B is not the same as a replacement 2B, yet they are given the same positional adjustment (+2.5).
2) To counteract biases in UZR. If corner infielders/outfielders all benefitted from playing an "easy" position (despite the fact that this is purely opinion). Like I mentioned before, this is simply not the case, so this cannot be a logical reason.
3. A purely opinionated judgment of how hard a certain position is. For example, saying that a CF with a positive UZR is worth x amount of runs more than a LF with the same UZR. Which I doubt is what they intended, because it would be pretty illogical for many reasons, and would not be based on data.
What do you guys think?