The Baggies enjoyed a blistering start to the season, amassing 33 points by the turn of the year but have faltered in 2013.
And Clarke, who saw his side emerge victorious from a Premier League encounter for only the fourth time since this year, feels it has been coming.
"We have been scratching for a win recently, and have become somewhat of a reactive team," he told Sky Sports after the 3-0 success.
"The performances haven't been all that bad in truth."
The result never really looked in doubt as Southampton offered very little in the final third, but the improvement in the visitors' performance pleased Clarke the most.
"It was important that we got the first goal," he added. "We talked about it beforehand and made sure that we started well.
"It was almost the perfect away performance."