When a piece is threatened you must sometimes move it backwards to stop a disaster. But "sometimes" is not "always".
Many players wants automatically to move a threatened piece backwards, easily missing the much better solution to move it forward. Moving forward could be the best defence. Think more like someone who wants to score a goal in football (soccer). Then you or a teammate must kick the ball forward.
Even a Grandmaster can fail to kick (move) forward.
Let's take a look at the game Levon Aronian - Shakhriyar Mamedyarov, Candidates Tournament 2014, Khanty-Mansiysk.
White played 13.f5.
Black played 13...Ne7?
and was lost after...
Even a Grandmaster can fail to kick (move) forward.
Let's take a look at the game Levon Aronian - Shakhriyar Mamedyarov, Candidates Tournament 2014, Khanty-Mansiysk.
White played 13.f5.
Black played 13...Ne7?
and was lost after...
14.Nde4!!
The black Queen is trapped.
14...dxe4 15.Nxe4 Qh4 16.g3 Qh3 17.Nf2 Qxf1+ 18.Kxf1 Nxf5
19.Qf3...1-0.
Black needs to play a more active defence after 13.f5.
There is one. Move forward.
13...Qg5!
Black threats to play Qxe3+ followed by Qxd3.
(13...Nh4 14.Qh5!)
14.Qe2 Nh4!
Black is OK.
The game Levon Aronian - Shakhriyar Mamedyarov at Chessgames.com and ChessVibes