What do you guys think? Dubious?
A good player(s) would never reach this position because they wouldn't have lost a tempo with 4. a3 or 4...a6, and they probably would have reacted with The Fork Trick after 5. Bc4 (via 5...Nxe4 6. Nxe4 d5) or 5...Bc5 (via 6. Nxe5 Nxe5 7. d4).
a3 doesnt lose a tempo...
For instance, after 4.a3 a6, now 5.d4 exd4 6.Nxd4 and black cannot play Bb4...
On 4.a3 (Gunsberg variation), black cannot really play 4...Bc5 5.Nxe5, so black has to chose between 4.d4 playing reverse, and 4...g6 playing Glek reverse.
On 4...d6, white may have a slight edge after 5.d4, black blocked his Bf8 bishop with d6, but they can play a kind of Ruy Lopez Steinitz position.
In all these variations, a3 can be useful, controlling b4 square, u can play b4 somtimes, and black cannot really avoid entering a reverse 4 knight.
So its an interesting reply, really not a loss of tempo.
There is a well known variation which has a good pedigree :
You don't say. Any other suggestion? The main reason why Capablanca is even today a good read is that no matter how simplistic it may seem, following some simple rules as for instance the one that knights are at their best when they are placed on f6 and c6, and poorly placed on a6,b6,g6 and h6 helps, but we are better than that, and anyway it's an old book that nobody ever reads.
This line for black might score against distracted players. Also works for white if black mirrors castling.
What do you guys think? Dubious?