user16771: Recently, I played a game and after running the computer analysis, it seems like playing 5. Ba4 was a mistake, being better Bxc6.

However, I cannot find the reason why. By retreating the bishop, White does not lose a pawn after ...Nfxe4. So I cannot see why my move would be a mistake.

user11629: The difference is that after Bxc6 you win a pawn with Nxe5. That's why the computer gives a +1 evaluation for it.
After Ba4 you end up with just an equal, normal position.
So it is rather the difference between going from better/won to equal than from equal to worse.

In fact 4...a6 is a weak move by black. Most popular and good is 4...Nxe4.

16771: <p>Recently, I played a game and after running the computer analysis, it seems like playing 5. Ba4 was a mistake, being better Bxc6.
<a href="https://i.stack.imgur.com/vWe2V.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vWe2V.jpg" alt="enter image description here"></a></p>

<p>However, I cannot find the reason why. By retreating the bishop, White does not lose a pawn after ...Nfxe4. So I cannot see why my move would be a mistake.</p>
 11629: <p>The difference is that after Bxc6 you win a pawn with Nxe5. That's why the computer gives a +1 evaluation for it.</p>

<p>After Ba4 you end up with just an equal, normal position.</p>

<p>So it is rather the difference between going from better/won to equal than from equal to worse.</p>

<hr>

<p>In fact 4...a6 is a weak move by black. Most popular and good is 4...Nxe4.</p>
