David Ripley bemoaned Northants' 'poor decision-making' after they were beaten again in the Royal London One-Day Cup on Friday.
The Steelbacks lost by 20 runs to Worcestershire Rapids after being bowled out for 234 at the County Ground.
Worcestershire had made 254 for nine after losing the toss, with Ben Sanderson, Nathan Buck, Rob Keogh and Josh Cobb claiming two wickets apiece.
But no Northants batsman could make a half-century as they lost for the fourth time in five 50-over matches this season.
“It’s very frustrating," Ripley said.
"It’s not the first time we’ve spoken about grabbing responsibility when chasing a score in 50-over cricket.
“There’s more decision-making to be made in 50-over cricket and that’s the bit we’re poor at.
“We’re either blocking our way into a hole or playing too loosely.
"Games like at Derby and here we should be winning."
Opener Hamish Rutherford was the star of the show for Worcestershire as he smashed 126 from 134 balls.
And Worcestershire first-team coach Alex Gidman said: “We were a little inconsistent but we won when not at our best - which is what you need to do to go far in competitions.
“The ninth-wicket partnership got us up to a really competitive score,
"Hamish played brilliantly, and then Brett (D'Oliveira) and Mitch (Daryl Mitchell) made a huge impact.
“We’re showing lots of skill-sets so far - you’re not going to play eight perfect matches to qualify - and we know we can improve on this come Sunday."