Downing is the temporary replacement for Steve Clarke who was sacked just over a week ago.
And, at the weekend, in his first game in charge, the Baggies came from behind to snatch a late point in the 1-1 draw with the Tigers at the Hawthorns.
It ended a four-match losing run and Downing said: "Maybe I didn't get the starting eleven right, because I had to change it at half-time.
"During games you get them right and get them wrong. But what I've got is a good set of substitutes and a good squad behind me, so I can look around on a matchday and think 'he can make an impact' and 'he can have an effect on the team'.
"The three lads on Saturday did that and it's about having that strength in depth and someone who can change the game."
As for West Brom's battle to escape relegation, he added: "You're always going to have the uncertainty of 'who is going to come in?' and 'hopefully I can impress'.
"At half-time against Hull we just tried to settle down a little bit because it was such a disruptive week.
"I just got the reflection of that in the first half and thought 'come on, boys, that's not us'.
"There was an edginess and a tension and we've got to try to settle things down and play with freedom and expression."