In the following position, databases of master games show black has a higher win rate (Lichess says 20% for white vs 25% for black). Why does black have a higher win rate here?
[FEN ""]
[StartPly "6"]
1. e4 e6 2. d4 d5 3. exd5 exd5
Stats from Lichess:
One possible reason:
Although black is in no way better after it, the move 3.exd5 is rather unambitious and increases the chances of a draw. Therefore it is more likely to be played in games where white is the weaker player.
Stefan already pointed out a hypothesis for this phenomenon and it appears to be accurate:
The average rating of people playing the move 3.exd5 in the lichess masters database is 2365, whereas the average rating of the move 3...exd5 (far and away the main move) is 2408, more than 40 rating points higher. This goes further too, in the resulting position the main moves are 4.Nf3 and 4.Bd3. These are even likely to transpose, however, the former is played by a rating average of 2388, the latter 2334. White scores much better with the first than with the second move despite their evaluation being virtually the same.
This is a not too rare phenomenon when just looking at the % scores so if you can, you should always check the players ratings too to gauge whether a good score is caused by the position or just by a rating disparity.
EDIT: Since it was requested, some more stats: the average rating after 1.e4 e6 2.d4 d5 appears to be approx. 2400 vs 2395. Meaning the exchange French is played by White players 35 rating points below that average against Black players 13 rating points above that average.
Other possible moves include: 3.Nc3 2406, 3.Nd2 2408, 3.e5 2384, 3.Bd3 2381. How to get these stats? In the lichess masters DB https://lichess.org/analysis you can hover over the WDL stat of a move to have the average rating be shown to you.
