Vladimir Coufal was annoyed about West Ham United conceding 'easy goals' in the loss to Arsenal.
The Hammers conceded two goals from set-pieces at London Stadium.
"We tried to do everything to get some points, but unfortunately we lost the game," Coufal told the club's website.
"We gave everything, tried to run everywhere, tried to put crosses into the box, but we conceded two easy goals from set-pieces."
He added: "It's always perfect when your reaction is like that not too long after you've conceded, especially when it's one minute before half-time.
"So it was the perfect time for an equalising goal and then we started perfectly in the second half to give ourselves a good position.
"But we conceded a bad second goal to give them the lead again."