The Austria global created the opener for Mark Noble midway through the first half, only for Joe Lolley to level things up with his first league goal of the campaign.
"We made too many easy mistakes which you can't do at this level".
Making such a mistake on his first home Premier League start could have easily affected the 25-year-old, but he responded in the flawless fashion by levelling things up before the break.
"With the second, 11 seconds into the second half, it was a very simple knock-down and we needed to be stronger and see the danger earlier".
"He is exactly the type of player that we like to work with at this club".
Newcastle United stretched their winless home run in the Premier League to seven games, and continued to slide towards the relegation zone after a 1-1 draw with bottom team Swansea City. Alex is a young British player who arrives as one of the top performers in the Sky Bet Championship and with a desire to prove himself in the Premier League.
The Terriers are now without a league win in their last five, where they have conceded nine goals in that time - a leaky defence which Wagner knows he must rectify if they are to see an upturn in results. "We know what we've done wrong today".
"Unfortunately not everything in football goes to plan".
Huddersfield had barely recovered from falling behind for a second time when they found themselves even further adrift, to the best goal of the day.
Just 11 seconds into the second half Arnautovic fired West Ham back into the lead as the Austrian forward turned and finished brilliantly to make it 2-1 to the Hammers.