Denis Betts says his Widnes team is making it easy for opponents because they keep switching off in games.
The Vikings trailed 14-6 at Hull at half-time on Friday, but the home side had extended their advantage to 26 points by the 52-minute mark.
Betts said: “We keep giving sides 18 points by rolling over in patches in the game – we’re making it easy for sides.
“We were up against a side running pretty hot with threats from all over the field, but I felt we handled them well for big patches of the game.
“We went toe-to-toe with them in the first half, which shows we’re not far off but then we hit a patch and look like a side that looks like it doesn’t know what it’s doing.
“We were defending our line well, but then we give penalties away and it takes energy out of our attack.
“The energy we wasted in conceding penalties is causing us some problems.
“I feel we’ve got two or three players under-performing, we’re lacking that cutting edge to break open a game.”