Since then, however, he has started every match with a lone striker and a midfield five.
This is partly down to personnel. Charlie Austin is still not 100 per cent fit and Kenneth Zohore, who looked sharp on Wednesday, now has a calf knock.
Hal Robson-Kanu has also been out with a back complaint, so Bilic hasn’t really had the opportunity yet.
Albion are also unbeaten in their first four games of the season – the start has been more than acceptable.
“At the moment the current system looks good for us,” said Bilic. “During the game sometimes we change it.
“We change the type of players in that system, for example, against Millwall and Reading we moved [Filip] Krovinovic to a holding midfielder. When we do that we’re taking a little bit more of a risk.”
Krovinovic’s form has been another factor. Impressive against Millwall, the Croatian playmaker has had a hand in Albion’s last two goals.
It was his shot which was deflected into Grady Diangana’s path at Luton, and he won the penalty at home to Reading.
“He’s a good player, and good players gel quicker,” said Bilic. “The good thing about him is he’s very reliable and responsible and he’s doing hard work.”
But Albion have also struggled with a lack of cutting edge up front so far.
Despite having plenty of the ball and an average of 17.5 shots per game, the Baggies are only averaging 3.75 on target.
Opposition goalkeepers are not being tested enough and too often, the team has given up promising counter-attacks by slowing play down and allowing their opponents to recover.
A lot of shots have been subsequently blocked by those bodies.
But two men up front may allow the Baggies to attack more quickly without waiting for the midfield to join, and there are tentative signs Zohore and Austin may fit together.
The big Dane seems to be better with his back to goal, laying the ball off, while Austin is a natural predator.
Do they have the potential to strike up a traditional big man/little man combination?
“It’s an option definitely, depending on the opponent, depending on our form, depending on the game,” said Bilic. “You don’t have to start with it, you can finish like that.
“The players we’ve got here gives us an option to play various systems.”
That would probably mean dropping Krovinovic, and giving up some of the ball in midfield.
It would heap more pressure on Romaine Sawyers and Jake Livermore, who have struck up a promising partnership behind the Croatian. Sawyers in particular, would be required to create more.
Krovinovic’s form makes that a bold move at this stage, and there are signs of more to come from the 4-2-3-1.
But if goals continue to be hard to come by, it might be worth trying the front two together.