Long grabbed his first goal of the season to equalise for the Baggies after an hour, then Steve Clarke's side took the lead through Stephane Sessegnon eight minutes later.
But Eden Hazard's penalty in stoppage time, awarded in controversial circumstances when Ramires tumbled in the penalty area under challenge from Steven Reid near the end of the four minutes added on, denied the Midlanders what would have been their second away win of the league campaign.
"We're disappointed, but we can hold our heads high," Irish international Long reflected.
"We defended really well as a team, sat in and frustrated them at times and caused them all sorts of problems on the counter-attack."
Long's goal was his first since he scored for the Republic of Ireland against England in May, and his first for his club since their defeat at Wigan earlier in the same month.
"Gareth McAuley had a great header," added Long. "To be fair it was a great save. It went straight up in the air and I just attacked it.
"I'm not too sure if I hit anyone on the way through. There was only one thing on my mind and that was the ball hitting the back of the net."