Recently I played a game with a fairly standard Ponziani opening when something slightly interesting occurred. The game started as thus:
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1.e4 e5 2.Nf3 Nc6 3.c3 Nf6 4.d4 Nxe4 5.d5 Ne7 6.Nxe5 d6
6...d6 here is, of course, not the main line; 6...Ng6 is a stronger move for Black, still threatening a capture on e5 in a way that develops the knight while also keeping the king relatively safe. In the single game I found in this position, White (Daniel Klocker, 8/30/2008) proceeded to play 7.Bb5+, which Stockfish seems to think is the best move possible. It gives this move roughly a six point advantage for White. Meanwhile, in the game I played, I instead played Qa4+. Chess.com classifies this move as a "mistake", and while it still calculates the position as being advantageous for White, the advantage decreases to a measly +2.4.
Why is this a poor move, though? When I was playing, my logic was this: if they play b5, then I play Qxb5+. If they play anything else, then I play Qxe4. In hindsight, perhaps it would be better to play Qxe4 in any case, or to maybe offer a queen trade if Qd7, but it seemed sound at the time. What is the downside of this move that I'm not seeing? White's queen isn't under attack here, and frankly, I'm not sure why Bb5+ is better since it's easily blocked by c6, forcing White to retreat instead of developing further.
