The home side let slip an 18-6 advantage to lead by only two at half-time but they regained their composure to keep the Tigers scoreless in the second half.
A try from Derrell Olpherts - converted by Krisnan Inu - confirmed victory for the Red Devils with 19 minutes remaining and saw Salford leapfrog Castleford into fifth place.
“It’s pretty frustrating,” admitted Powell. “We are trying to piece our game together and we are just not that great at the minute. As a team we are just not firing.
“We can’t find accuracy and fluency in attacking positions to score points which is something we’ve been able to do in the past.
“We just have to keep going. There are some players who are not good enough to be in the team at the moment. Players have got to find their best form.
“As disappointing as it is, it’s a reality. As a team we are not flowing. We have got to hang tough and find a way back.”
Despite his disappointment, he was still able to pay tribute to Salford and said: “Their enthusiasm was fantastic and too much for us.
“Salford did a lot of the real basics of rugby league and they deserved to win. We are hard to watch at the minute.”