Carroll has been out of action since injuring his knee against Southampton back in February and has been busy stepping up his training ahead of his latest comeback.
Many Hammers fans feel they simply cannot rely on the injury-prone striker anymore despite co-owner Sullivan giving the former Liverpool man his backing in an interview with the Sunday Times.
The Hammers chief has backed new manager Slaven Bilic in the transfer market to the tune of £25 million this summer but the club are yet to recruit a striker despite having just Diafra Sakho as a proven Premier League goalscorer.
While many fans consider the 6ft 5in Geordie something of an expensive bonus for their side, Sullivan has told the Sunday Times he “can’t wait” for Carroll's return and says people are wrong to judge him.
“People think he’s out partying all the time," Sullivan told the Sunday Times.
"He’s not. Our fitness guys will tell you he’s doing the hardest training of his life.
"You may see an Andy Carroll you’ve never seen before. He could be devastating.”
You've changed your tune
Despite suffering two long-term injuries during his initial season on loan from Anfield, the Hammers were unperturbed and pressed ahead with sanctioning a club record £18 million permanent deal on a six-year contract.
But Sullivan's latest views are in stark contrast to his feelings on the subject 18 months ago.
That's because the outspoken Hammers chief admitted he wouldn't have done the deal with the benefit of hindsight back in 2013, as reported by BBC's Football Focus.
He said at the time: "Had we known he would be out for this long, we would not have signed him, we are not a rich enough club to deal with that."
Latest return is a big boost ... but for how long?
The former Newcastle United forward is expected to return to the first team in the first two weeks of September.
And that could provide a huge boost for Bilic who has seen back-up striker Carlton Cole released and £12 million Ecuardorian striker Enner Valencia sidelined with injury for up to three months.
The Upton Park faithful have been left somewhat frustrated with Carroll's injury woes, especially as Sullivan's fellow co-owner David Gold told fans he would be available for the first game of the new season.
He wasn't and when he eventually does cynics say he will only be injured again after three or four games back.
Broken record signing
In the two years since making his move to east London permanent, Carroll has made just 27 appearances, scoring seven goals.
He has suffered four major injuries in that time. His absence is exacerbated by the fact the club even inexplicably wasted more than £10 million on flop Matt Jarvis to provide the ammunition for the England star.
No-one is doubting the target man's work ethic and quality when fit. But the trouble is that he rarely is ever fit.
Everyone at West Ham will be hoping he can buck the trend and get his career back on track again for both club and country on his return.