With his replacement, Michael Carrick, leading United to back-to-back victories, Amorim has been hammered by Sharpe's peers in the media.
But Sharpe says Amorim did some good things for United before being dumped this month.
He told Tribalfootball.com: "I liked Amorim, to be fair to him, and I think a lot of people did.
"I think he spoke well, he got rid of a little bit of the sort of bad eggs in the club, which was not easy to deal with, and he did a lot of things right.
"But I do think that a good coach picks a team and a formation around the players he's got, and Amorim was very stubborn in his three at the back, which has never really been a Man United way.
"Having seen what Michael's done in these first two games against the two top teams in playing a four at the back, it's like a different team with a different mentality, and it just goes to show what the players can do."
Fulham a barometer
Sharpe continued: "We've got to wait for Fulham (this weekend), and we've got to wait for when it's not such a big game, and maybe they're not quite up for it, who knows.
"But certainly, going back to basics, going back to what the players know, keeping things simple and creating an air of sort of urgency, confidence and belief in each other, and working for each other.
"I know Amorim added that to a certain degree, but I suppose you could say complicated would be the word.
"I think he might have mentally complicated people. From hearing what he did in training with long, slow sessions, which was just trying to drill things into people.
"You go into games really flat, really mentally tired and get caught between one thought and another.
"Carrick has certainly made things a lot clearer to the players and gone out with an intensity and a purpose which we've seen in the performances so far."
Too early to call
Asked if Carrick has already done enough to land the manager's job long-term, Sharpe insists no decision should be rushed.
He added: "I think without getting a little bit too excited, like we did a little bit with Ole Gunnar Solskjaer when he first came in, we do have to give it time, because United have been renowned to step up a gear against the big teams, and then, for example, like in the next game against Fulham, to go and drop off a gear and to get beat or drop points.
"So, I do think you have to be a little bit patient and a little bit cautious. But if he continues with this style of play and gets these results that get us into the top four, then I don't see why he can't be the main candidate for the job for sure."
- Lee Sharpe was speaking to Tribalfootball on behalf of Betway
