Crewe's on-loan Fulham striker Lauri Dalle Valle netted his third and fourth goals of his short stay at Gresty Road as the hosts cruised to a 2-0 victory with a second-half performance as dominant as their first-half showing was inadequate.
Crawley's last league win was against MK Dons on October 23 and they have taken only three points from their last six league matches.
After Saturday's defeat, Barker said: "The first half everybody was really positive but the second half I was struggling to pick out anybody. If there's a game that proves that no two halves of football are ever the same, that is one of those games.
"I was positive with my players at half-time. But in the second half, the conditions got a little bit worse with a stiff breeze and we never really got going. Nicky Adams was providing some good deliveries into the box, but we didn't create any clear-cut chances from any of them. There was just no desire to get on the end of them."