A narrow opening-day defeat at home to Edinburgh was followed by another defeat at Thomond Park in round four against Ospreys.
Despite the losses Munster still have five wins from seven and sit in fourth place - one spot above reigning champions Leinster.
And with a solid league position O'Callaghan believes the squad are beginning to show what they are capable of.
With several key players away on international duty, Munster produced a dogged performance to snatch out a result at Cardiff Blues - much to the delight of the veteran Irish lock.
"Eleven fellas leaving for Irish camp, there's a bit of a void but you have to step up when you're given your chance and the lads did that against Cardiff," he told the Irish Independent.
"But now I think we are reflecting work. I know the coaches won't be happy with performance against Cardiff, but I think just to get the win is great.
"We were frustrated at the start of the season especially with the Edinburgh and Ospreys game where we didn't really reflect a week's work that went into us.
"The coaching staff are doing an incredible amount of work. Everything is prepped for us and then as a player you don't go out and don't respond and don't do well, you feel bad, and I think that was a case where it totally lies with the players."
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