Manager Rodgers and the legion of Reds supporters at The Hawthorns were given a reality check as goals from Zoltan Gera, Peter Odemwingie (penalty) and Romelu Lukaku sealed their fate.
In addition defender Daniel Agger was sent off for a professional foul when conceding the first of two spot-kicks awarded to the Baggies.
Only poor finishing prevented West Brom from doubling their tally while at the other end of the pitch Liverpool striker Luis Suarez spurned two gilt-edged opportunities.
Rodgers said: "There is a big job to do and we will have more days like this along the way. That is the reality of it. It is still a work in progress.
"There will be days along the way that will hurt and it will be difficult for us.
"It is going to take time. Hopefully we won't have too many days like that and we will keep moving forward."
Rodgers knows his side have to be more clinical in front of goal and Suarez, for all his brilliant approach play, needs to increase his conversion rate of chances.
The Reds boss said: "The reality of the situation is we need to score more goals. If we are going to affect the top of this league, we have got to score more goals."
Rodgers felt his side were harshly done by in terms of the two spot-kicks awarded against them by referee Phil Dowd - the first of which from Shane Long was saved by Pepe Reina.
He said: "I like Phil. He is normally a good ref for me. We are not going to get everything our way.
"A couple of harsh decisions went against us, we never scored our chances and West Brom took full advantage of the extra man.
"But the players have been brilliant since I came here and gave everything at West Brom. They ran themselves to a standstill."
Rodgers admitted to being concerned over the recurrence of substitute Joe Cole's hamstring injury which led to him being taken off.
He said: "It is strange because Joe had trained all pre-season very well and then got injured in our first European game with Gomel.
"He came back, did well in training, came on at Albion for 10-15 minutes and the hamstring has happened again. It is something the medical people will have to look at."
New Albion boss Steve Clarke believes his former club - he was assistant to Kenny Dalglish - will revive their fortunes although he admitted to approaching the game in a positive frame of mind.
He said: "Liverpool are a top team with really good players and for me they will be up there challenging for the top four this season. But I expected to win.
"I'm quite a confident person. It doesn't always come across in my demeanour or manner but I knew I had a good group, that they were ready for the game and they proved me right.
"Sometimes you look at one of the top teams coming and you think it can be a really difficult afternoon.
"But I was asking the players to make sure it was a difficult afternoon for Liverpool - and that's what they did."
Clarke admits having Gera available is "like a new signing" after he missed all but three games of last season with ankle and knee ligament problems.
He said: "Zoltan has had a difficult time with injuries but he has worked so hard to get back to this position.
"It is like a new signing for us really. He has come back and he might be getting on in years, but he is enthusiastic and wants to be part of what we are trying to do here."