Jimmy Gopperth's late penalty denied the Welsh region the small consolation of a losing bonus point, while Saints skipper Dylan Hartley's try earned his side something in Castres. That upped the ante for their trip to Franklin's Gardens where Wales and British & Irish Lions prop Jones insists Ospreys must improve.
"There were a few harsh words said after the game from the coach [Steve Tandy] which we probably needed. As a squad we said a lot during the week but failed to back it up on the pitch," said Jones.
"We didn't do ourselves justice at all and butchered a few chances early on, so that's something we now have to put right at Northampton."
The front row battle will be critical at Franklin#s Gardens with Hartley going head to head with Lions hooker Richard Hibbard, but there will be no reunion of Lions props Alex Corbisiero and Jones. The Englishman has been ruled out with injury.
"Alex was brilliant during the Lions tour so it's good news for us he's not there. They lost a few big guys in the summer like Brian Mujati and Soane Tonga'uiha but we know they have a physical edge up front and we have to match that," said Jones..
"Despite what happened last week, we are still confident about going to Northampton. We know what we did wrong against Leinster and they are all things we can put right.
"It has been a tough week in training and Steve [Tandy] has given us a real telling off but we know if we do the things we are good at then we can beat most teams."