bg2 is necessary because white already implied it by going g3. nf3 is not. ne2 can be tried, as is the weird nh3. both are not better than nf3 but it may force black to think for himself earlier than he would like.
Catalan 4. Nf3 or Bg2
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Jul 21, 2023
0
#3
Catalan move order often depends on Black.
Two things need to happen to reach a Catalan:
1) ...e6 must be played. If the Bishop can come out still for Black, g3 isn't very good.
2) ...Nf6 must be played if you want to take advantage of the Stonewall Dutch.
It is well known that 1.d4 f5 2.c4 Nf6 3.Nc3 e6 4.Nf3 that 4...Bb4 is very strong and the 4...d5 is basically a Blunder due to 5.Bf4, 6.e3, and 7.Bd3. If that setup is still possible for White, then the Stonewall is a blunder, hence why Black waits for g3 before stonewalling.
So going back to the Catalan, the 2 different defenses for Black lead to 2 different move orders for White.
Against those that start 1...Nf6 and 2...e6, like Nimzo players, both quotas are already met after 2 moves. To prevent the Queen's Indian, you want to play 3.g3! immediately! 1.d4 Nf6 2.c4 e6 3.g3! d5 4.Bg2 and now Black has 4...Be7, 4...c6, or 4...dxc4.
Against the Queen's Gambit Declined, 1.d4 d5 2.c4 e6, the Bishop is blocked (item 1), but not the f-pawn. If you play 3.g3 now, then 3...f5! gets Black a good version of the Stonewall instead of the bad one demonstrated earlier. Now 3.Nc3 allows Bb4 pinning lines, like the Ragozin. So Catalan players will play 3.Nf3!, and once Black blocks the f-pawn with 3...Nf6 (3...f5?? Is again bad due to 4.Bf4! and 5.Nc3, 6.e3, 7.Bd3), only then 4.g3!
So in summary:
Nimzo move order: 1.d4 Nf6 2.c4 e6 3.g3 d5 4.Bg2
QGD move order: 1.d4 d5 2.c4 e6 3.Nf3 Nf6 4.g3
Jul 21, 2023
0
#4
to answer ops question specifically, chess.coms database ranks moves by how much the position after they are played was reached
e.g. e4 f5 and a whole bunch of random moves come above the only move any top player would play, exf5 BECAUSE those positions were reached after xx f5 e4
(this is a flaw of the database imo and idk why chess.com has it this way)
so
maybe Bg2 was played more from that position, but the position after Nf3 was reached more
Using the chess.com opening explorer, black's replies to either move are the same. Yet the explorer shows:
4. Nf3 27,010
4. Bg2 7,297
This indicates that bringing the knight out first is just a habit? Or if you go deeper beyond black's 4th move, the position of the knight or bishop makes a difference?