The West Ham boss started with three centre-backs enabling him to play Aaron Cresswell and Michail Antonio wide – with the aim to hit target man Andy Carroll and let him do the rest.
“We knew that sometimes that we would have space on the flanks and we could use it to put in good crosses,” he said.
“We have a few players who are capable of bending a ball really well. If they put the ball into the box it is up to Andy.
“I told them before that we expected to have time and space on their flanks.”
Carroll scored three times, and could have been sent off, in a six-goal thriller.
Bilic changed the system at half time because they were struggling defensively, but they continued to threaten.
Arsenal led 2-0 before a Carroll double on the stroke of half time.
West Ham v Arsenal - Premier League match preview
He completed his hat-trick seven minutes into the second half before Laurent Koscielny equalised.
“I’m proud of everything,” Bilic said.
“We were spectacular. The only thing I’m not happy with is the result. Why? Because this is a blow. To be fair we’ve had enough blows.
“We deserve to be even third in the league and unfortunately we are not so it is a blow.