The former Bafana Bafana striker was speaking after their 2-1 Premier Soccer League loss against his former mentor, Gavin Hunt at Athlone Stadium on Saturday evening.
McCarthy lamented their poor and erratic defending and said the Clever Boys did not threaten them, but errors led to the defeat.
The Citizens had the favourites tag heading to the encounter after bagging four wins over the Students in all competitions this term.
However, striker Lehlohonolo Majoro, who joined the PSL champions in January, netted a brace to stun McCarthy’s side and Craig Martins scored for the hosts.
“With the way the game had gone‚ with the chances we created‚ we needed a number nine‚ a poacher‚ to put it in for us,” McCarthy said on Times Live.
"We will just pray that Matthew (Rusike) is not too serious and it is just a tweak that he felt. Our lapses in concentration at crucial times cost us," he continued.
The former FC Porto, Celta Vigo and West Ham United forward added that the Braamfontein side did not play well either, but were lucky to score.
Resulting from this defeat, City now occupy the sixth spot with 31 points from 22 matches and trail log leaders, Mamelodi Sundowns, with nine points.
"It wasn’t like they (Wits) played to deserve the goals they scored‚ it was bad defending. Two mistakes from (Taariq) Fielies‚ who is usually ever so reliable,” added the 40-year-old.
“It was a bad day in the office for him and he disappointed his teammates. We were in control of the game‚ we had the better of our opponents," he continued.
“It was three points lost for us to be honest. All we can do is just go and rectify our mistakes because we are playing really good football,” concluded McCarthy.
Up next for the Mother City side is a trip to the Limpopo province where they will face Baroka FC on Tuesday at Peter Mokaba Stadium.