"We should have trounced Munster and earned a bonus point. But we were hugely unprofessional at times and what we did in the lineout was unacceptable," Matt Williams argued.
The result may have been Ulster's fourth straight home win since the Australian's arrival in Belfast but their overall performance was below par and their lineout, despite the presence of returning captain Rory Best, malfunctioned throughout the 80 minutes.
Williams felt that his side had been let off the hook as an understrength Munster team failed to make the most of their possession in the interprovincial clash.
"Munster didn't turn up (tonight) and it is very rare that you get a Munster side that don't turn up.
"We should have got a bonus point, we should have flogged them. To give Munster that amount of possession, on any other night I've seen Munster play, they'd do you by a huge score," Williams admitted.
"I thought we let ourselves down by our own standards. We wanted to play attractive rugby and when we did we looked okay, but our backs didn't get enough quality ball."
Tries from Rob Dewey, Ryan Caldwell and Andrew Trimble were enough for Ulster to run out 19-9 winners, with the victory moving them eight points clear of Connacht in the race to secure the final Irish qualifying spot in next season's Heineken Cup.
With two home games remaining against the Glasgow Warriors and Cardiff Blues, Ulster should have enough in the tank to keep ahead of Connacht.
But Williams reckons his side's failure to claim the full five points against Munster could come back to haunt them as Connacht still have a mathematical chance of pipping them.
"We got the four points but we should have got the five. We should be in there (the Heineken Cup) now and I should be able to play all my young guys and learn a bit about them in the next two weeks. It should be over.
"But now we still have a bit of a job to do so there is a whole lot of things there. It's young side that needs to be more professional. We gave away a lot of silly penalties and things like that."
Asked about his views on the Ireland coaching position and the speculation linking Munster boss Declan Kidney with the job, Williams became the second provincial coach this week to give the Corkman the thumbs up.
"Declan has been very successful and he fits the profile. He has won the Heineken Cup, a really big trophy.
"He has a great profile for international coaching. He has been at this level for a long time, had a lot of contracts and has been with a couple of other clubs.
"He has also been there at international level as an assistant so he understands what it's like. Personally I hope he gets it and I think he'll do a very good job because I think he will bring a lot of maturity to the position," he added.