Downing assumed the reins at The Hawthorns last weekend following the dismissal of Clarke and the former assistant expects everyone in the squad to step up and force their way into contention.
Several players were bereft of regular first-team opportunities, most notably Graham Dorrans, Goran Popov, James Morrison, Saido Berahino and Nicolas Anelka, all of whom have missed out for a variety of reasons.
However, Downing insists there will be preconceived judgements as he takes charge of his first game on Saturday as West Brom host Hull City.
"There is now a new set of eyes on them," Downing told the Birmingham Mail. "We have 23/24 players who all want to be in the starting line-up.
"It's a clean slate and it freshens things up. Someone might want something different, so everyone comes into the equation."
Downing has managerial experience of his own having took charge of Cheltenham between November 2007 and September 2008 but admits there is much more media exposure to contend with in the top flight.
"Cheltenham was managing and getting the best out of players," he added.
"But no-one knew about Cheltenham - I used to sit in front of one journalist a week, not as many as you do in the Premier League.
"It was good experience. I benefited enormously. I've improved as a No.2 as a result of that. I have a bit of integrity and humility and think 'come on, I have to do better."