After collecting seven points from their first three games against Liverpool, Tottenham and Everton, this always looked likely to be an excellent season for the Baggies.
At one point they appeared live contenders for a European slot before they began to slither down the table, and they head into Saturday's encounter with Newcastle having collected just four points from their last five games.
Yet they remain on track for their highest league finish since 1981.
And, given the strength of the sides in front of them, it may be as much as any West Brom team can reasonably expect.
"If you look at what happened to us this year then no, it's probably not realistic to sustain it over a full season," Clarke said.
"It's something we have to look at. The fact is we had a really strong start and then we tailed off.
"I mentioned some weeks ago we have to look at why, in the middle block of the season, the club had a dip, in this year and previous ones."