Chelsea won 1-0 thanks to Nicolas Jackson's first-half goal, which came after Beto coughed up possession to Trevoh Chalobah on the lead-up.
Moyes said afterwards: "You see it in football all the time.
"We played the ball into the centre-forward's feet, he does not retain possession and the opposition go on and score.
"We don't accept it but the modern game sees lots of players do it. We are trying to play better and these are the things we need to be better at."
The Scot also said of the game overall, "We were perhaps fortunate to only be 1-0 at half-time but we stuck at it, grew into the game and played very well in the second half. We were just lacking quality to get a finish on the end of some of our play.
"The subs made a big difference. It looked like we had more energy and were more creative."