McCarthy left the Upton Park outfit after his contract was prematurely terminated by mutual consent after being left out of West Ham's Premier League squad for the second half of the campaign.
"I don't really know when I last spoke to him (Grant) - but he's got a lot on his plate at the moment," the 33-year-old told Sky Sports News.
"I'm sure he could help his position if he'd maybe take a little bit more time to speak to players more. That's what you do if you are a manager and you have a good relationship with players, you get results.
"But I'm not the type of person to go to a manager and give them ultimatums - they make decisions on what they see in training.''
The South African striker failed to score a single Premier League goal after arriving at the Hammers in January 2010 and admitted he had let himself down.
"I let myself down. I just went hiding under a rock because I couldn't deal with the fact I was injured.
"I never trained how I could train because obviously I was out for two months (with a calf injury) so I wasn't allowed to train or anything - it was just treatment, treatment, treatment.''