David Ripley admits Northants' 'brittle' batting is costing them dear after seeing his side suffer their third defeat of the season on Sunday.
The County were beaten by six wickets at Edgbaston as Warwickshire overcame some early scares in the second innings to get the job done.
Northants set Warwickshire 179 to win after being bowled out for 187 in their second innings.
Ben Sanderson took three early wickets, but the home side rebuilt and Will Rhodes' unbeaten century proved to be the match-winning innings.
Northants have now lost three of their first four matches in County Championship Division Two, with the other game, against Durham, a total washout.
It is not the start to the season the County had hoped for and they will now look to improve as they head into the Royal London One-Day Cup, which starts on Thursday.
"For a long time it was a very even game and at lunchtime today it was really in the balance after we took those two key wickets just before lunch," Ripley said.
"I thought it was going to the wire, but Will Rhodes played really well under pressure.
"To get a hundred with your team under pressure on a wearing pitch showed good skill and determination and he was the difference."
Northants have injury issues to contend with ahead of the 50-over game against Leicestershire Foxes at the County Ground this week.
Richard Gleeson is definitely out with an elbow injury, while Nathan Buck is still recovering from an Achilles problem.
And Steven Crook has now been added to the injury list after picking up a problem at Edgbaston.
"We just have to hope the injury is nothing too serious for Steve so he doesn't miss too much cricket," Ripley said.
"We won nine championship matches last year and have the same squad so we know we are a better side than the league table shows at the moment but it's a tough division and if you don't play well you are going to get beaten.
"At the moment, particularly batting, we are proving to be brittle.
"We only have three championship fifties and no hundreds - we have got to improve that to be competitive and stay in games for longer."