Asked if Arsenal's fluency had returned, Wenger said: "In patches, it's always a different game after the Champions League, mentally it's so demanding. The players questioned themselves after a few draws.
"We got better during the game but Bournemouth played well. They started with high intensity physically and when I saw that I thought they would drop a little bit in the second half.
"After that we were a bit unlucky because I think there was a second penalty on Sanchez and the penalty for them is another questionable one. After that, we had to improve our level in the second half."
The result sees Arsenal climb to fourth in the Premier League table, three points behind leaders Chelsea.